Is ultrasound-guided radiofrequency ablation reliable for unifocal T1aN0M0 papillary thyroid carcinoma in the isthmus: A retrospective cohort study

Is ultrasound-guided radiofrequency ablation reliable for unifocal T1aN0M0 papillary thyroid carcinoma in the isthmus: A retrospective cohort study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Is ultrasound-guided radiofrequency ablation reliable for unifocal T1aN0M0 papillary thyroid carcinoma in the isthmus: A retrospective cohort study Gongli Zhou, Dong Xu, Beibei Zhang, Ruiqing Su, Ke Xu, Xuefeng Zhang, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4734711/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract 431 patients who underwent ultrasound-guided RFA for unifocal T1aN0M0 papillary thyroid carcinoma (PTC) were divided by location of the lesion into the PTCI group (52 females, 7 males, mean age 43.79 ± 12.04 years, range 22–74 years) and the PTCL group ((291 females, 81 males, mean age 43.42 ± 10.87 years, range 18–75 years) for comparative analysis. The efficacy of ultrasound-guided RFA was evaluated by volume reduction rate (VRR), complete disappearance rate (CDR), and disease progression, and the safety was evaluated by incidence of complications. The two groups exhibited a consistent trend of change, with the PTCI group performing slightly better in volume, VRR, and CDR at all follow-up time points expect 1 month. The mean initial volume of the PTCI group vs the PTCL group decreased significantly from 65.4 ± 69.79 vs 86.38 ± 87.09mm³ (range 10.92-427.58 vs 3.05-471.6mm³) to 0 vs 0 mm³ at a mean follow-up time of 31.12 ± 12.5 months (range 12–60 months); their VRR increased significantly from − 618.62 ± 655.61% vs -789.85 ± 1135.07%, at 1 month to 100% vs 100% at 48 months. No disease progression was found in the two groups. The PTCI group had no complications, whereas the PTCL group had 7 complications (1.88%). Ultrasound-guided RFA is reliable for unifocal T1aN0M0 PTCI in the isthmus. Biological sciences/Cancer Health sciences/Diseases Health sciences/Endocrinology Health sciences/Oncology radiofrequency ablation thyroid papillary carcinoma volume reduction rate complete disappearance rate hydro-dissection Figures Figure 1 Figure 2 Figure 3 Introduction Thyroid cancer (TC), which represents around 3% of all human cancers worldwide in recent years [ 1 ], has attracted extensive attention due to its rising incidence [ 1 – 4 ]. The age-standardized incidence of TC worldwide in 2018 revealed by International Agency for Research on Cancer reached 6.7/100000, with 10.2/100000 among women vs 3.1/100000 among men [ 1 ]. In the United State, the incidence of TC surged from a stable level at 5/100000 before the mid-1990s to 15.0/100000 in 2014 [ 2 ]. From 1970 to 2012, the age-standardized incidence of TC in Canada increased from 1.5/100000 to 7.2/1000000 in men and from 3.9/100000 to 23.4/100000 in women [ 3 ]. From 2005 to 2015, the age-standardized incidence of TC in China ascended from 3.21/100000 to 9.61/100000, with the annual percent change reaching 12.4% [ 4 ]. However, the mortality rate of TC has remained at a low level in spite of its rapidly increasing incidence rate [ 5 ]. In the United States, the average incidence-based mortality of TC was 0.40/100000 during 1994–1997 and 0.46/100000 during 2010–2013 [ 6 ]. In Canada, the mortality of TC remained at approximately 0.5/100000 for both men and women from 1970 to 2012 [ 3 ]. The estimated crude mortality rate of TC in China was 0.58/100000 in 2015, with 0.44/100000 among men and 0.73/100000 among women [ 4 ]. Papillary thyroid carcinoma (PTC), accounting for 85%-90% of all TC cases [ 7 , 8 ], has been identified to be the dominant contributor to the increasing incidence of TC worldwide [ 9 ]. The increased detection of PTC has been ascribed to widespread examination of unrelated neck conditions using Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI) or Ultrasound (US), improvement in detection and diagnosis of asymptomatic nodules discovered incidentally, and nation-wide screening of nodules through regular physical examination [ 10 – 12 ]. PTC, which is a well-differentiated and mostly clinically unapparent histological subtype of TC, is featured with slow growth, low malignancy and comparatively favorable prognosis [ 13 , 14 ]. The majority of PTCs would never cause any problems if left undiagnosed or untreated [ 15 ]. Therefore, an increasing number of experts advocated a conservative approach rather than immediate thyroidectomy, lobectomy and isthmusectomy for the management and treatment of PTC [ 16 – 18 ]. A small portion of PTC lesions arise from the isthmus, which lies directly anterior to the trachea in a relatively shallow location where the gland becomes thinner and narrower. Thyroid carcinoma in the isthmus (PTCI) was reported to account for 2.5%-12.3% of all PTC cases [ 19 – 22 ]. PTCI usually has extremely obvious early symptoms, which is conducive to timely detection and treatment. Compared to papillary thyroid carcinoma in the lobe (PTCL), PTCI is more aggressive and risky, reflected by its higher probability of multifocality, lymphovascular invasion and extraglandular infiltration [ 20 , 23 – 24 ]. Although major guidelines and consensuses have proposed thermal ablation as an alternative to surgical resection for selected patients with PTC, there is still no recommended treatment approach for PTCI to date [ 25 – 33 ]. There are many controversies among scholars regarding the treatment of PTCI. No reliable conclusions have been drawn due to the underrepresentation of the sample in the small number of relevant clinical studies. Despite the increasing acceptance of RFA as a pre-surgery treatment of low-risk PTC worldwide, RFA is not recommended in China for PTC in the isthmus [ 31 ]. Hence, we retrospectively evaluated the efficacy (assessed by tumor volume reduction rate, tumor complete disappearance rate and disease progression) and safety (assessed by incidence of complications) of ultrasound-guided radiofrequency ablation (RFA) for unifocal T1aN0M0 PTC using sustained, large-sample data. We also compared the data of patients with PTCI and with PTCL during the same period to more accurately evaluate whether ultrasound-guided RFA can be a reliable treatment option for selected patients with PTCI. Methods This retrospective study was approved by the Ethics Committee of Hangzhou Weja Hospital. Written informed consent was obtained from each patient prior to the implementation of RFA. Definition of PTCI Surgical anatomy defines the isthmus as the band-shape tissue which is located anterior to the trachea and connects the left and right thyroid lobes [ 35 ], but there are no clear boundaries for its two sides. The isthmus under ultrasound is defined as the tissue between the two virtual lines on the thyroid gland perpendicular to the outermost bilateral boundaries of the trachea [ 36 ]. As suggested by Lim et al. [ 22 ], we draw two vertical lines perpendicularly from the outermost points of the trachea on both sides to the skin according to the results of a preoperative color ultrasound evaluation of the thyroid and neck lymph node. The central point of a tumor was designated as the intersection point of its longest and shortest diameters. If the central point of the tumor was located between the two virtual lines, the tumor was considered to be located in the isthmus. Fine-needle aspiration (FNA) was performed in view of its advantages in preoperative diagnostic evaluation of thyroid tumors and neck lymph node metastasis including minor trauma, high safety, high diagnostic accuracy and good reproducibility [ 37 ]. As shown in Fig. 1 , we defined the tumor with its central point between the two virtual lines and confirmed by FNA to be PTC as papillary thyroid carcinoma in the isthmus (PTCI). Patients We selected patients with unifocal T1aN0M0 PTC defined by The American Joint Committee on Cancer TNM staging system for DTC [ 34 ], which categorizes T1 differentiated thyroid carcinoma (DTC, maximum tumor diameter ≤ 20mm) into T1a (maximum tumor diameter ≤ 10mm) and T1b (10mm<maximum tumor diameter ≤ 20mm), from all the PTC patients who underwent RFA in Hangzhou Weja Hospital from March 2019 to March 2023. In this definition, N0 suggests no regional lymph node metastasis and M0 suggests no distant metastasis. The patients selected were divided by location of the lesion into the PTCI group (consisting of patients with unifocal T1aN0M0 PTC in the isthmus) and the PTCL group (consisting of patients with unifocal T1aN0M0 PTC in the lobe) for comparative analysis. The inclusion criteria were: 1) Patients revealed by ultrasound to have an appropriate route for FNA; 2) Patients confirmed by ultrasound-guided FNA to have PTC; 3) Patients with unifocal T1aN0M0 PTC within the thyroid gland; 4) Patients who had anxiety about the existence of the tumor in their body, refused active surveillance and surgical treatment, and required to receive ablation treatment; 5) Patients who have been followed up no less than 12 months after RFA; 6) Patients who accepted the anonymous use of their data for clinical research. The exclusion criteria were: 1) Patients with evidence of lymph node metastasis; 2) Patients with evidence of distant metastasis; 3) Patients with evidence of capsule contact/invasion or extrathyroidal extension; 4) Patients with severe coagulation mechanism disorders; 5) Patients with dysfunction or failure of important organs (e.g. brain, heart, liver and kidney). Finally, we included 431 patients in this study. Instruments and equipment We used Voko color Doppler ultrasound diagnostic instrument and L741 high-frequency linear-array probe, and set the probe frequency to 12MHz. We chose Type L-121 disposable RFA needles and MedSphere radiofrequency therapy instrument (produced by MedSphere International, Inc.) for the implementation of RFA, with the frequency set to 400KHz. Pre-RFA assessment Ultrasound-guided assessment was conducted on each tumor prior to RFA to examine its three orthogonal diameters (i.e. the maximum diameter and the other two perpendicular diameters), position, shape (height/width), calcification, echo, contour, vascular density, internal structure and anatomical adjacency. Each patient underwent full-range examinations including imaging, coagulation function, thyroid function, and complete blood count examinations before RFA. If the PTCI lesion clung to the trachea, normal saline was injected for hydro-dissection during preoperative FNA to test whether the lesion can be successfully completely separated from the trachea. According to the Hydro-dissection Trial (HDT) Theory proposed by Weja Hospital, only the PTCI lesions that can be successfully completely separated from the trachea are eligible for RFA. All the patients were informed of the rationale, procedure, precautions, and possible complications of RFA, and signed an informed consent prior to RFA. RFA procedure RFA was performed by experienced surgeons proficient in using ultrasound equipment, ultrasound-guided puncture technology, hydro-dissection technology and RFA instrument. The patient was positioned supine. The shoulders were elevated to completely expose the neck. Routine disinfection and draping were performed on the neck. Local anesthesia was performed by injecting 2% lidocaine under ultrasound guidance. For the patients whose lesion was close to the trachea, recurrent laryngeal nerve, esophagus or carotid artery, a hydro-isolation zone was formed by injecting an appropriate amount of hydro-dissection material (i.e. normal saline, 5% glucose, sodium hyaluronate gel, or 5% glucose & sodium hyaluronate gel) once or more times with a 23-gauge needle to keep a distance > 5mm between the lesion and adjacent tissues and organs (Fig. 2 ). It should be noted that for patients with diabetes, normal saline was used for hydro-isolation as recommended in "Expert consensus on thermal ablation for thyroid benign nodes, microcarcinoma and metastatic cervical lymph nodes (2018 edition)" [ 31 ]. The radiofrequency therapy instrument was adjusted to have an output power of 15W. Under ultrasound guidance, the 18G electrode was inserted deepest into the lesion and positioned appropriately. Next, the treatment started using the "pull-back" technique and the moving shot technique via the isthmus. Expanded ablation at least 2 mm beyond the boundary of the original lesion was used to avoid lesion residue or recurrence. The treatment ended when a transient hyperechoic zone completely covered the lesion. The ablated tissue was examined by contrast-enhanced ultrasound (CEUS) immediately after RFA to determine whether the lesion was completed ablated. If there was contrast perfusion into the ablated tissue, supplementary RFA was performed immediately to eliminate any residual lesion. Post-RFA evaluation and follow-up After RFA, each patient underwent 1–2 hour observation in the treatment room. Their physical conditions and potential complications were closely monitored and recorded. They were discharged after another 3–5 hour continuous observation in case of no abnormalities. After RFA, the patients underwent regular follow-ups at 1, 3, 6, 12, 18, 24 months and 12 months thereafter. Ultrasound-guided thyroid and functional examinations were performed to evaluate the following indicators: 1) Volume of the ablated tissue (V), calculated as V (mm³) = abcπ/6 (a is the maximum diameter, while b and c are the other two diameters perpendicular to a) [ 25 ], as shown in Fig. 3 ; 2 ) Volume reduction rate (VRR), calculated as VRR = (initial volume of the tumor - follow-up volume of the ablated tissue)/initial volume of the tumor×100% [ 38 ]; 3) Complete disappearance rate (CDR), calculated as CDR = number of cases of complete absorption followed-up/total number of patients followed-up∗100%, where the ablated tissue changing to a linear scar was considered to indicate complete absorption; 4) Number of cases of lymph node metastasis, new occurrence and local recurrence confirmed to be PTC by ultrasound-guided FNA of suspicious nodules that were evaluated by thyroid and neck lymph node ultrasound; 5) number of cases of distant metastasis revealed by Computed Tomography (CT) or Positron Emission Tomography-Computed Tomography (PET-CT) at every two years after RFA or in case of suspicious symptoms; 5) Number of deaths caused by recurrent or metastatic PTC. Statistical processing The data collected were analyzed and compared using SPSS software (SPSS for Windows 21.0). The categorical data were expressed in numbers and percentages and compared using chi-square test. The quantitative data that conformed to normal distribution and homogeneity of variance were expressed as mean ± standard deviation (SD) and compared using independent sample t-test. The data of volume before and after RFA were compared using paired sample t-test. For all comparisons, a difference with P < 0.05 was considered statistically significant. Results Pre-RFA outcomes We included a total of 431 patients who underwent ultrasound-guided RFA for unifocal T1aN0M0 PTC at Hangzhou Weja Hospital between March 2019 and March 2023, and divided them into 59 cases in the PTCI group (with the lesion located in the isthmus) and 372 cases in the PTCL group (with the lesion located in the lobe). The cases of PTCI accounted for 13.69% of all the PTC cases included, slightly higher than the data reported previously [ 19 – 22 ]. This minor deviation may be due to the inclusion of only unifocal T1aN0M0 PTC in this study rather than all types of PTC. The baseline pre-FRA outcomes of the two groups are shown in Table 1 . The two groups had no statistically significant differences in gender, age, maximum diameter, aspect ratio and calcification ( P > 0.05), indicating their comparability. Table 1 Pre-RFA outcomes of the two groups Variable PTCI(N = 59) PTCL(N = 372) P Gender 0.810 Male 7(11.86%) 81(21.77%) Female 52(88.14%) 291(78.23%) Age 0.906 5 35(59.32%) 205(55.11%) Aspect ratio 0.703 <1 29(49.15%) 117(31.45%) ≥1 30(50.85%) 255(68.55%) Calcification 0.998 Calcification 25(42.37%) 158(42.47%) No calcification 34(57.63%) 214(57.53%) RFA outcomes According to Table 2 , the PTCI group had a mean age of 43.79 ± 12.04 years, while the PTCL group had a mean age of 43.42 ± 10.87 years, with no statistically significant difference ( P = 0.809). The PTCI group had a maximum diameter of 5.64 ± 1.62mm before RFA, while the PTCL group had a maximum diameter of 5.73 ± 2.03mm, with no statistically significant difference ( P = 0.733). The PTCI group had a tumor volume of 65.4 ± 69.79mm³ before RFA, slightly lower than that of the PTCL group (86.38 ± 87.09mm³), but the difference was not statistically significant ( P = 0.079). The ablation time of the PTCI group was 151.92 ± 134.77s, slightly higher than that of the PTCL group (120.93 ± 122.51s), but the difference was not statistically significant ( P = 0.076). The ablation power was 23.36 ± 9.62w in the PTCI group and 22.12 ± 9.08w in the PTCL group, with no statistically significant difference ( P = 0.334). The follow-up period was 31.12 ± 12.5 months in the PTCI group, and 28.59 ± 11.03 months in the PTCL group, with no statistically significant difference ( P = 0.112). The results in Table 2 show that the two groups had no statistically significant differences in pre-RFA tumor size, RFA-related indicators and follow-up period ( P > 0.05). Table 2 RFA outcomes of the two groups Variable PTCI PTCL P Max Min Mean ± SD Max Min Mean ± SD Age (years) 74 22 43.79 ± 12.04 75 18 43.42 ± 10.87 0.809 Pre-RFA max diameter (mm) 10 3.1 5.64 ± 1.62 10 1.9 5.73 ± 2.03 0.733 Pre-RFA volume (mm³) 427.58 10.92 65.4 ± 69.79 471.6 3.05 86.38 ± 87.09 0.079 Ablation time (s) 600 27 151.92 ± 134.77 1200 10 120.93 ± 122.51 0.076 Ablation power (w) 45 15 23.36 ± 9.62 50 9 22.12 ± 9.08 0.334 Follow-up period (m) 60 12 31.12 ± 12.5 60 12 28.59 ± 11.03 0.112 Post-RFA outcomes Tables 3 − 1 and 3 − 2 show the ablated tissue volume, VRR, and CDR of the two groups at 1 (M1), 3 (M3), 6 (M6), 12 (M12), 18 (M18), 24 (M24), 36 (M36) and 48 months (M48) after RFA. According to Table 3 − 1, the volume of the PTCI group was 288.67 ± 210.48mm³at M1, significantly larger than the tumor volume (65.4 ± 69.79mm³), showing a statistically significant difference ( P < 0.001). Because of expanded ablation, the ablation tissue was much larger than the original tumor in size. The part absorbed 1 month after RFA was still much smaller than the tissue outside the original tumor that was ablated. The volume of the PTCI group was 108.42 ± 122.02mm³ at M3, slightly higher than the initial volume, but the difference was not statistically significant ( P = 0.086), indicating that the ablated tissue gradually decreased in size and approached the original tumor volume as time progressed. From M6, the volume was significantly smaller than the initial volume, and the differences were statistically significant ( P < 0.05): it was 30.68 ± 45.56mm³ at M6, 2.75 ± 7.01mm³ at M12, 0.31 ± 1.46mm³ at M18, 0.2 ± 0.98mm³ at M24, and 0mm³at M36 and M48. According to Table 3 − 1, the VRR of the PTCI group was − 618.62 ± 655.61% and − 127.68 ± 257.35% respectively at M1 and M3, both negative because the ablated tissue was still greater than the initial tumor in size before 3 months. From M6, the ablated tissue was smaller than the initial tumor, so that the VRR turned positive and gradually increased: it was 39.64 ± 117.48% at M6, and significantly increased to 95.9 ± 11.78% at M12, 98.9 ± 5.16% at M18, 99.28 ± 3.44% at M24, and 100% at M36 and M48. The CDR was 1.69% at M1, 11.86% at M3, 40.68% at M6, 74.58% at M12, 93.62% at M18, 94.44% at M24, and 100% at M36 and M48. Table 3 − 1 Post-RFA volume, VRR and CDR of the PTCI group Time point V(mm³) P VRR(%) CDR Max Min Mean ± SD Max Min Mean ± SD Cases CDR(%) M1 758.9 0 288.67 ± 210.48 < 0.001 100 -2016.77 -618.62 ± 655.61 1/59 1.69 M3 572.22 0 108.42 ± 122.02 0.086 100 -1136.75 -127.68 ± 257.35 7/59 11.86 M6 143.37 0 30.68 ± 45.56 0.009 100 -462.5 39.64 ± 117.48 24/59 40.68 M12 32.37 0 2.75 ± 7.01 < 0.001 100 43.42 95.9 ± 11.78 45/59 74.58 M18 6.87 0 0.31 ± 1.46 < 0.001 100 75.79 98.9 ± 5.16 44/47 93.62 M24 4.68 0 0.2 ± 0.98 < 0.001 100 83.5 99.28 ± 3.44 34/36 94.44 M36 0 0 0 ± 0 < 0.001 100 100 100 ± 0 21/21 100 M48 0 0 0 ± 0 < 0.001 100 100 100 ± 0 6/6 100 Note: P in this table was a statistical result of comparison between the ablated tissue volume at each follow-up time point and the initial volume before RFA. According to Table 3 − 2, the volume change trend of the PTCL group was roughly similar to that of the PTCI group. The ablated tissue was significantly larger than the initial tumor in size at M1, and the difference was statistically significant ( P < 0.05). From M6, the ablated tissue was significantly smaller than the initial tumor in size, and the differences were statistically significant ( P < 0.05). The first dissimilarity between the two groups in tumor volume change was found at M3: the volume of the PTCI group was slightly higher than the initial volume, and the difference was not statistically significant ( P = 0.0860), whereas the volume of the PTCL group was significantly higher than the initial volume, and the difference was statistically significant ( P < 0.001). This should be attributed to the narrow space in the isthmus which limited the scope for ablation expansion. Probably for this reason, the volume of the PTCI group was basically smaller than that of the PTCL group, as shown in Table 3 – 3 . Besides, the ablated tissue was completely absorbed earlier in the PTCI group than in the PTCL group. The changes in VRR and CDR in the PTCL group were similar to those in the PTCI group. Table 3 − 2 Post-RFA volume, VRR and CDR of the PTCL group Time point V(mm³) P VRR(%) CDR Max Min Mean ± SD Max Min Mean ± SD Cases CDR(%) M1 2027.25 0 415.55 ± 359.78 < 0.001 100 -8576.77 -789.85 ± 1135.07 6/372 1.61 M3 1049.74 0 144.96 ± 193.54 < 0.001 100 -3602.14 -188.74 ± 486.15 30/372 8.06 M6 775.83 0 45.78 ± 85.16 < 0.001 100 -1542.52 0.53 ± 225.73 118/372 31.72 M12 276.33 0 11.71 ± 35.61 < 0.001 100 -133.27 84.09 ± 39.07 250/372 67.2 M18 133.25 0 2.95 ± 13.28 < 0.001 100 -30.64 94.34 ± 19.54 265/297 89.23 M24 95.98 0 2.24 ± 10.13 < 0.001 100 9.86 96.04 ± 14.95 198/212 93.4 M36 22.89 0 0.67 ± 3.21 < 0.001 100 81.14 99.11 ± 3.54 90/93 96.8 M48 0 0 0 ± 0 < 0.001 100 100 100 ± 0 18/18 100 Note: P in this table was a statistical result of comparison between the ablated tissue volume at each follow-up time point and the initial volume before RFA. Table 3 – 3 shows the results of comparison between the two groups in volume, VRR, and CDR after RFA. At M1, the volume of the PTCI group was significantly lower than that of the PTCI group, and the difference was statistically significant (P < 0.05). This can be attributed to the smaller scope for expanded ablation in the PTCI group due to the small size of the isthmus to avoid thermally damaging adjacent tissues and organs. Except for a significant difference in volume at M1, the volume of the PTCI group was slightly lower than that of the PTCL group at all the follow-up time points between 6 and 36 months, but the differences were not statistically significant ( P > 0.05). As for VRR, at all the follow-up time points between 1–36 months, the PTCI group had a higher VRR than the PTCL group, but the differences were not statistically significant ( P > 0.05). The same trend occurred in the changes in CDR: at all the follow-up time points between 1–36 months, the CDR of the PTCI group was higher than that of the PTCL group, but the differences were not statistically significant ( P > 0.05). At M48, the two groups were identical in volume, VRR, and CDR. Table 3 3 Comparison of the two groups in Post-RFA volume, VRR and CDR Time point V(mm³) P VRR(%) P CDR(%) P PTCI PTCL PTCI PTCL PTCI PTCL 0.603 M1 288.67 ± 210.48 417.93 ± 368.9 0.035 -618.62 ± 655.61 -789.85 ± 1135.07 0.337 1.69 1.61 - M3 108.42 ± 122.02 144.96 ± 193.54 0.264 -127.68 ± 257.35 -188.74 ± 486.15 0.491 11.86 8.06 - M6 30.68 ± 45.56 45.78 ± 85.16 0.345 39.64 ± 117.48 0.53 ± 225.73 0.383 40.68 31.72 - M12 2.75 ± 7.01 11.71 ± 35.61 0.146 95.9 ± 11.78 84.09 ± 39.07 0.082 74.58 67.2 - M18 0.31 ± 1.46 2.95 ± 13.28 0.354 98.9 ± 5.16 94.34 ± 19.54 0.28 93.62 89.23 - M24 0.2 ± 0.98 2.24 ± 10.13 0.338 99.28 ± 3.44 96.04 ± 14.95 0.303 94.44 93.4 - M36 0 ± 0 0.67 ± 3.21 0.437 100 ± 0 99.11 ± 3.54 0.352 100 96.8 - M48 0 ± 0 0 ± 0 - 100 ± 0 100 ± 0 - 100 100 - Table 4 shows hydro-dissection, incidence of complications, and disease progression after RFA in the two groups. 5% glucose and 5% glucose & sodium hyaluronate gel were used for hydro-dissection more frequently in both groups. The PTCI group did not have any complications, while the PTCL group had a total of 7 complications (1.88%), including 4 cases of hoarseness or hoarseness (recovering within 3 months after RFA without treatment) and 3 cases of coughing during drinking water (recovering within 1–4 weeks after RFA without treatment). Regarding disease progression, neither group was found to have lymph node metastasis, distant metastasis, new tumors, local recurrence, or death caused by PTC during the follow-up period. Table 4 Hydro-dissection, complications and disease progression in the two groups Variable PTCI(N = 59) PTCL(N = 372) Hydro-dissection 59(100%) 358(96.24) Normal saline 5(8.48) 7(1.88) 5% glucose 26(44.07) 309(83.07) Sodium hyaluronate gel 3(5.08) 2(0.54) 5% glucose & sodium hyaluronate gel 25(42.37) 40(10.75) No 0(0) 14(3.76) Complication 0(0) 7(1.88) Thickening or hoarseness of voice 0(0) 4(1.08) Coughing during drinking water 0(0) 3(0.08) Dysphagia 0(0) 0(0) Bleeding or infection 0(0) 0(0) Tracheal or esophageal injury 0(0) 0(0) Permanent recurrent laryngeal nerve injury 0(0) 0(0) Parathyroid injury 0(0) 0(0) Thyroid dysfunction 0(0) 0(0) Disease progression 0(0) 0(0) Lymph node metastasis 0(0) 0(0) Distant metastasis 0(0) 0(0) New tumor 0(0) 0(0) Local recurrence 0(0) 0(0) Deaths caused by PTC 0(0) 0(0) Discussion The results of our cohort study confirm the effectiveness and safety of RFA as a treatment option for unifocal T1aN0M0 PTC in the isthmus. The results show basically no differences between the PTCI group and the PTCL group in volume change, VRR, CDR, incidence of complications and disease progression. Specifically, the VRR and the CDR of the PTCI group were slightly higher than those of the PTCL group at all the time points within 36 months. All the PTCI lesions were fully absorbed up to 36 months, and all the PTCL lesions were fully absorbed up to 48 months, without disease progression during the follow-up period. The PTCI group did not have any compilations, while the PTCL group had a total of 7 compilations (1.88%). In a comparative study of 181 PTCI cases and 1792 PTCL cases, Lee et al. argued that total thyroidectomy should also be performed during initial treatment based on their findings that PTCI was more likely to invade the capsule and have multifocal lesions at an early stage and that PTCI had higher incidence of lymph node metastasis in zone VI and lower incidence of lateral lymph node metastasis [ 21 ]. Nixon et al. analyzed 19 PTCI cases and recommended isthmusectomy as a treatment option for low-risk PTCI because it did not affect the patient's survival rate and also protected the recurrent laryngeal nerve and parathyroid gland from injury [ 23 ]. Although lobectomy has been recommended as a less radical alterative to total thyroidectomy for PTC limited to a single lobe and detected at an early stage, no clear therapeutic strategy for PTC restricted in the isthmus is found in the guidelines [ 25 – 33 ]. Most T1aN0M0 PTC tumors were found to remain indolent, clinically silent and small over time, and delayed surgery was performed only when disease progression was detected during the surveillance of node metastasis or tumor growth [ 39 ]. For this reason, active surveillance has been proposed as a tailored approach for the management of T1aN0M0 PTC. This targeted approach was initiated by Kuma Hospital in 1993 as an alternative to immediate surgery and aggressive treatment in the context of overtreatment [ 40 ]. Kuma Hospital conducted a series of long-term observation trials [ 17 , 40 – 41 ], with the longest one lasting for 30 years [ 17 ], and reported extremely low rates of tumor size enlargement and new cases of node metastasis during 10-year, 22-year and 30 year follow-ups to support their proposal of active surveillance. In their latest observation, they found ≥ 3mm tumor size enlargement only in 3.8% patients who underwent active surveillance, tumor size enlargement in 4.7% and 6.6% active surveillance cases respectively in 10 years and 20 years, novel lymph node metastases in 0.8% active surveillance cases, no deaths caused by TC, and no significant clinical differences between low-risk PTC patients who underwent immediate surgery and underwent active surveillance [ 17 ]. During the roughly same period, Cancer Institute Hospital carried out a 5-year (ranging from 1 to 17 years) observation of 300 patients with low-risk asymptomatic PTC and found tumor size enlargement in only 7% patients, occurrence of lymph node metastases in 1% patients, and no new occurrence of distant metastases or extrathyroidal extension [ 42 ]. These favorable outcomes of active surveillance clearly demonstrate that surgery is necessary only for an extremely small proportion of patients with low-risk PTC. From the perspective of the patient's survival rate, the implementation of surgery for selected patients detected to have disease progression during the observation period is deemed to be as effective as immediate surgical resection. Hence, periodic follow-up has been recommended as an option superior to immediate surgery for T1aN0M0 PTC in view of its good prognosis [ 13 , 26 – 27 ]. However, the natural history of more aggressive PTC tumors with lymph node metastasis and distant metastasis detected during initial screening or early follow-up should be better understood to determine the optimal management strategy [ 43 ]. Despite the feasibility of active surveillance for T1aN0M0 PTC, some patients have varying degrees of anxiety and unease about the existence of PTC in their body. Most patients are more willing to accept relatively positive intervention measures rather than just active surveillance. In view of the essential function of active surveillance in mitigating the overtreatment of low-risk PTC featured with an indolent nature, local ablative therapies which are not potentially harmful but useful and reasonably priced may be a less invasive means to treat TC in patients who are unable or refuse to accept their cancer untreated, but they should not replace necessary resection therapies [ 18 ]. Ultrasound-guided thermal ablation has been confirmed by a large number of studies to be effective and safe for T1aN0M0 PTC and has been widely used in clinical practice for the treatment of T1aN0M0 PTC [ 44 – 48 ]. As pointed out by Chinese Ultra Sound Doctors Association, thermal ablation is easy to operate, precise in positioning, safe and effective in inactivating the tumor before disease progression to alleviate patients' psychological pressure [ 32 ]. The consensus released by Chinese Ultra Sound Doctors Association specifies the indications and contraindications of using thermal ablation to treat T1aN0M0 PTC, and provides a detailed, complete explanation of the preoperative diagnosis of T1aN0M0 PTC [ 32 ]. A number of guidelines and consensuses given by multiple associations also mention that for T1aN0M0 PTC discovered by chance, thermal ablation is a potential alternative to active surveillance and immediate surgical resection provided that the patient refuses or is not qualified for surgery, and is unwilling to undergo active surveillance [ 25 – 31 ]. In "Expert consensus on thermal ablation of papillary thyroid cancer (2024 edition)", the latest PTC-targeted consensus jointly released by several leading associations and committees in China based on a large number of convincing empirical results, thermal ablation is highly recommended as one of the first-line treatment methods for T1aN0M0 PTC in view of its similar treatment outcomes to surgical resection and its evidence-supported advantages over surgical resection including minimal invasiveness, low incidence of complications, no need to accept lifelong hormone replenishment, short operative time, fast postoperative recovery, and high quality of life after RFA [ 33 ]. Radiofrequency ablation (RFA), in virtue of its minimal invasiveness, predictable, safe and easy procedure, low incidence of complications, and high-quality postoperative life, has been recommended in recent years as a potential remedy option for benign thyroid nodules and TC [ 47 – 50 ]. Its effectiveness in treating unifocal PTCI was also confirmed in a retrospective study by General Hospital of Chinese PLA, where it was found that all the lesions performed with ultrasound-guided RFA were successfully ablated and completely disappeared at 18 months without any complications, lymph node metastasis and abnormal thyroid function and that the VRR was 97.6 ± 5.2% and 99.6 ± 1.8%, respectively at 6 months and 12 months [ 51 ]. However, the application of RFA in malignant thyroid tumors is still controversial [ 52 ]. In a clinical analysis of 5 patients who underwent surgery after RFA, it was found that non-standard implementation of RFA caused anatomical boundary ambiguity and local tissue adhesion, which increased difficulty in following surgical operation [ 53 ]. The reason was attributed to unfamiliarity with tumor biological behavior and anatomy. To ensure successful RFA treatment and minimize potential complications, the operator is required to be familiar with thyroid anatomy and ultrasound images, proficient in using RFA-related instruments and equipment, and skilled in avoiding potential complications [ 54 ]. Besides, the use of hydro-dissection materials during RFA is an important way to protect adjacent tissues and other important structures. "Expert consensus on thermal ablation of thyroid cancer (2024 edition)" also highlights the requirements on operators, including obtaining relevant qualifications, proficient ultrasound examination and image recognition, proficient puncture techniques, proficient hydro-dissection techniques, proficient use of thermal ablation instruments, and rich experience in thermal ablation of benign thyroid tumors [ 33 ]. The 0 incidence of complications in the PTCI group may be partially attributed to the implementation of Hydro-dissection Trial (HDT) during FNA, which functioned in ensuring that PTCI lesions can be successfully completely separated from the trachea. We ascribe these favorable outcomes to the effectiveness and safety of RFA, the selection of unifocal T1aN0M0 PTC cases, the implementation of HDT during FNA initiated by Hangzhou Weja Hospital in selected PTCI cases, and the proficiency of the RFA operator. However, our study has certain limitations. Firstly, the data were collected from a single center, suggesting the need for multicenter results to support the conclusions drawn here. Secondly, the follow-up period is not long enough to evaluate disease progression that may occur when the observation time is extended. Thirdly, we did not evaluate whether RFA has a similar effect in treating multifocal T1aN0M0 PTC. Fourthly, we did not evaluate whether RFA increases the difficulty of subsequent surgical operation in the case of disease progression since no participant was performed with surgery after RFA. In conclusion, the results of our study indicate that RFA is a reliable treatment option for unifocal T1aN0M0 PTC, either in the lobe or in the isthmus, in view of its effectiveness in slowing down tumor progression or outward metastasis and its high safety demonstrated by our large-sample data. We recommend the setting of strict inclusion criteria for patients selected to perform RFA, the implementation of HDT during FNA, and the training of proficient RFA operators to ensure the reliability of RFA in treating PTC. Declarations Acknowledgments Dr. Gongli Zhou, who is president of Hangzhou Weja Hospital, envisioned the prospect of research into fields related to thyroid and has been insisting on engaging patients in follow-ups to collect their data since the establishment of the hospital. This study would not have been possible without his permission and support. The authors gratefully acknowledge the assistance provided by staff at Hangzhou Weja Hospital and the instructive support from Chinese Academy of Sciences. Author Contributions Z. G. and X. D. performed conceptualization, data curation, methodology, project administration, supervision and review. Z. B. took charge of formal analysis, investigation and resources. S. R. performed data curation, visualization and writing. X. K. and Z. X. performed formal analysis, investigation and editing. L. F., Z. W and C. T. took charge of recourses, software and visualization. Data Availability Statement The output data used to support the findings of this study are included within the article. The detailed patient data used to support the findings of this study are restricted by the Ethics Committee of Hangzhou Weja Hospital in order to protect PATIENT PRIVACY. Data are available from Gongli Zhou ( [email protected] ) for researchers who meet the criteria for access to confidential data. Funding Information No commercial interest or funding is involved in this study. Competing Interests Statement The authors have no conflict of interest. Ethics Statement This retrospective study was approved by the Ethics Committee of Hangzhou Weja Hospital (No. 2024004) and was completed in accordance with the revised guidelines of the Declaration of Helsinki (2013). Written informed consent was obtained from each patient prior to the implementation of RFA. Registry and the Registration No. of the study/trial: N/A; Animal Studies: N/A. References Ferlay, J. et al . Estimating the global cancer incidence and mortality in 2018: Globocan sources and methods. International Journal of Cancer 144 , 1941-1953 (2019). National Cancer Institute. SEER cancer statistics review, 1975-2014. SEER Statistics, 2018. 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Society of Tumor Ablation Therapy of the Chinese Anti-Cancer Association, Ablation Expert Committee of the Chinese Society of Clinical Oncology (CSCO), Chinese Medical Doctor Association College of Interventionalists Tumor Ablation Committee, Chinese Bethune Spirit Research Association Endocrinology and Diabetes Branch Interventional Endocrine Committee. Expert consensus on thermal ablation of papillary thyroid cancer (2024 edition). Chinese Journal of Internal Medicine 63 , 355-364 (2024). Berg, A. N. & Seethala, R. R. The American joint committee on cancer eighth edition. AJSP Review and Reports 23 , 145-148 (2018). Cao, X. et al . Microwave ablation for papillary thyroid cancer located in the thyroid isthmus: a preliminary study. International Journal of Hyperthermia 38 , 114-119 (2021). Hahn, S. Y., Han, B. K., Ko, E. Y., Shin, J. H. & Ko, E. S. 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Sugitani, I., Toda, K., Yamada, K., Yamamoto, N., Ikenaga, M. & Fujimoto, Y. Three distinctly different kinds of papillary thyroid microcarcinoma should be recognized: our treatment strategies and outcomes. World Journal of Surgery 34 , 1222-1231 (2010). Durante, C. et al . Identification and optimal postsurgical follow-up of patients with very low-risk papillary thyroid microcarcinomas. Journal of Clinical Endocrinology & Metabolism 95 , 4882-4888 (2010). Cao, X. et al . Efficacy and safety of thermal ablation for treatment of solitary T1N0M0 papillary thyroid carcinoma: A multicenter retrospective study. Radiology 300 , 209-216 (2021). Han, Z. et al . Safety and efficacy of microwave ablation for the treatment of low-risk papillary thyroid microcarcinoma: a prospective multicenter study. European Radiology 33 , 7942-7951 (2023). Kim, H. J. et al. Long-term efficacy of ultrasound-guided laser ablation for papillary thyroid microcarcinoma: Results of a 10-year retrospective study. Thyroid 31 , 1723-1729 (2021). Zhang, M. et al . Ultrasound-guided radiofrequency ablation versus surgery for low risk papillary thyroid micro-carcinoma: Results of over 5 years follow-up. Thyroid 30 , 408-417 (2020). Yan, L., Li, X., Li, Y., Xiao, J., Zhang, M. & Luo, Y. Comparison of ultrasound-guided radiofrequency ablation versus thyroid lobectomy for T1bN0M0 papillary thyroid carcinoma. European Radiology 33 ,730-740 (2022). Tang, X. et al . Evaluation of the safety and efficacy of radiofrequency ablation for treating benign thyroid nodules. Journal of Cancer 8 ,754-760 (2017). Zhang, M., Luo, Y., Zhang, Y. & Tang, J. Efficacy and safety of ultrasound-guided radiofrequency ablation for treating low-risk papillary thyroid microcarcinoma: A prospective study. Thyroid 26 , 1581-1587 (2016). Song, Q. et al . Evaluation of ultrasound-guided radiofrequency Ablation as a Treatment Option for Papillary Thyroid Microcarcinoma in the Isthmus: A Retrospective Study. Frontiers in Endocrinology 11 (2021). Shi, K. & Zheng, C. Application progress of radiofrequency ablation in thyroid diseases. Cancer Research and Clinic 30 , 429-432 (2018). Zhang, H. & Dong, W. Current situation and thoughts on radiofrequency ablation in the treatment of thyroid cancers. Chinese Journal of Surgery 55 , 574-578 (2017). Xu, S., Liu, D. & Liu, C. Radiofrequency ablation therapy for thyroid nodules. International Journal of Endocrinology and Metabolism 33 , 243-246 (2013). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4734711","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":335284612,"identity":"098e3651-e13b-480b-9456-be2a5ccf6fb7","order_by":0,"name":"Gongli Zhou","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuUlEQVRIiWNgGAWjYNCCAgk5Nvb2A6RoMZAw5uM5k0CSFobEeRIOBsQplu9ffOzhFwOL9DYJhgSGHxXbCGthnPEs3VjGQCK3TbrxAGPPmduEtTBLnDGTlgBpkTmQwMzYRoQWNqiWdDaJBAPitPDw95hJfjCQSCBei4QEW5o0MJAN24CBfJAov8j3Hz4m+aOiTl6+vf3ggx8VRGhhkEhgYOaBsg8QoR4I+A8wMP4gTukoGAWjYBSMVAAAAK40m9B4GCsAAAAASUVORK5CYII=","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":true,"prefix":"","firstName":"Gongli","middleName":"","lastName":"Zhou","suffix":""},{"id":335284613,"identity":"4790f020-1a99-496f-809f-1c40ff2e4bdc","order_by":1,"name":"Dong Xu","email":"","orcid":"","institution":"Zhejiang Cancer Hospital, Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Dong","middleName":"","lastName":"Xu","suffix":""},{"id":335284614,"identity":"1d60f61b-d5f7-46f2-b8fd-88c353daf0ae","order_by":2,"name":"Beibei Zhang","email":"","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":false,"prefix":"","firstName":"Beibei","middleName":"","lastName":"Zhang","suffix":""},{"id":335284615,"identity":"5a6f1f2c-2b77-4ce8-ad9c-73e24953a190","order_by":3,"name":"Ruiqing Su","email":"","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ruiqing","middleName":"","lastName":"Su","suffix":""},{"id":335284616,"identity":"7d4aabc3-cf47-40c9-b5b9-295d6d60f37d","order_by":4,"name":"Ke Xu","email":"","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ke","middleName":"","lastName":"Xu","suffix":""},{"id":335284617,"identity":"edaf3ceb-e89e-48e9-b359-d324977f9e8a","order_by":5,"name":"Xuefeng Zhang","email":"","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xuefeng","middleName":"","lastName":"Zhang","suffix":""},{"id":335284618,"identity":"c97b10d6-c0b5-4953-9259-415156ad3a94","order_by":6,"name":"Feng Li","email":"","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":false,"prefix":"","firstName":"Feng","middleName":"","lastName":"Li","suffix":""},{"id":335284619,"identity":"1e8b108b-0177-47a1-8520-94ee3242f5f5","order_by":7,"name":"Wei Zhao","email":"","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":false,"prefix":"","firstName":"Wei","middleName":"","lastName":"Zhao","suffix":""},{"id":335284620,"identity":"c5101bba-f9cf-4495-acf1-95f6e8444535","order_by":8,"name":"Tingting Cai","email":"","orcid":"","institution":"Hangzhou Weja Hospital","correspondingAuthor":false,"prefix":"","firstName":"Tingting","middleName":"","lastName":"Cai","suffix":""}],"badges":[],"createdAt":"2024-07-13 10:12:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4734711/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4734711/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":62220195,"identity":"a52d7b9d-d51a-4b66-b9d1-8217b7d1a6f1","added_by":"auto","created_at":"2024-08-11 12:19:58","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":97817,"visible":true,"origin":"","legend":"\u003cp\u003eLocation of the isthmus and definition of PTCI: the tumor with its central point between the two virtual lines perpendicularly from the outermost points of the trachea on both sides to the skin and confirmed by FNA to be PTC was considered to be papillary thyroid carcinoma in the isthmus (PTCI).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4734711/v1/ad4985948c1f5903a45a4782.png"},{"id":62220196,"identity":"e2be581a-9ba2-40eb-9fcc-c7f9b737b7a5","added_by":"auto","created_at":"2024-08-11 12:19:58","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":137525,"visible":true,"origin":"","legend":"\u003cp\u003eUltrasound images of the lesion before and after injection of hydro-dissection: (a) before injection of hydro-dissection; (b) after injection of hydro-dissection\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4734711/v1/3c41700a89f7f1d9973fa33d.png"},{"id":62221428,"identity":"0e5b22c2-ff6d-462e-bd04-e145d137b4c4","added_by":"auto","created_at":"2024-08-11 12:27:58","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":213884,"visible":true,"origin":"","legend":"\u003cp\u003eVolume changes of a 38-year-old female patient with PTCI: (a1-a2) The initial volume of the tumor before RFA was 55.83mm³ (a=5.9mm, b=4.3mm, c=4.2mm); (b) The volume of the ablated tissue was 164.27mm³ (a=7.6mm, b=7.5mm, c=5.5mm) at 1 month after RFA; (c) The volume of the ablated tissue was 36.78mm³ (a=4.5mm, b=4.0mm, c=3.9mm) at 3 months after RFA; (d) The volume of the ablated tissue was 11.91mm³ (a=2.9mm, b=2.8mm, c=2.8mm) at 6 months after RFA; (e) The ablated tissue was completely absorbed at 12 months after RFA.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4734711/v1/581068900e98aea2dd03bd98.png"},{"id":67650741,"identity":"73411e19-7d5b-47b3-9e6b-016105c4bc82","added_by":"auto","created_at":"2024-10-28 11:39:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1352764,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4734711/v1/ffcdb192-b334-4fc9-b428-fc917b703cca.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Is ultrasound-guided radiofrequency ablation reliable for unifocal T1aN0M0 papillary thyroid carcinoma in the isthmus: A retrospective cohort study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThyroid cancer (TC), which represents around 3% of all human cancers worldwide in recent years [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], has attracted extensive attention due to its rising incidence [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The age-standardized incidence of TC worldwide in 2018 revealed by International Agency for Research on Cancer reached 6.7/100000, with 10.2/100000 among women vs 3.1/100000 among men [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In the United State, the incidence of TC surged from a stable level at 5/100000 before the mid-1990s to 15.0/100000 in 2014 [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. From 1970 to 2012, the age-standardized incidence of TC in Canada increased from 1.5/100000 to 7.2/1000000 in men and from 3.9/100000 to 23.4/100000 in women [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. From 2005 to 2015, the age-standardized incidence of TC in China ascended from 3.21/100000 to 9.61/100000, with the annual percent change reaching 12.4% [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, the mortality rate of TC has remained at a low level in spite of its rapidly increasing incidence rate [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In the United States, the average incidence-based mortality of TC was 0.40/100000 during 1994\u0026ndash;1997 and 0.46/100000 during 2010\u0026ndash;2013 [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. In Canada, the mortality of TC remained at approximately 0.5/100000 for both men and women from 1970 to 2012 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The estimated crude mortality rate of TC in China was 0.58/100000 in 2015, with 0.44/100000 among men and 0.73/100000 among women [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePapillary thyroid carcinoma (PTC), accounting for 85%-90% of all TC cases [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], has been identified to be the dominant contributor to the increasing incidence of TC worldwide [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The increased detection of PTC has been ascribed to widespread examination of unrelated neck conditions using Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI) or Ultrasound (US), improvement in detection and diagnosis of asymptomatic nodules discovered incidentally, and nation-wide screening of nodules through regular physical examination [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. PTC, which is a well-differentiated and mostly clinically unapparent histological subtype of TC, is featured with slow growth, low malignancy and comparatively favorable prognosis [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The majority of PTCs would never cause any problems if left undiagnosed or untreated [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Therefore, an increasing number of experts advocated a conservative approach rather than immediate thyroidectomy, lobectomy and isthmusectomy for the management and treatment of PTC [\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA small portion of PTC lesions arise from the isthmus, which lies directly anterior to the trachea in a relatively shallow location where the gland becomes thinner and narrower. Thyroid carcinoma in the isthmus (PTCI) was reported to account for 2.5%-12.3% of all PTC cases [\u003cspan additionalcitationids=\"CR20 CR21\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. PTCI usually has extremely obvious early symptoms, which is conducive to timely detection and treatment. Compared to papillary thyroid carcinoma in the lobe (PTCL), PTCI is more aggressive and risky, reflected by its higher probability of multifocality, lymphovascular invasion and extraglandular infiltration [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough major guidelines and consensuses have proposed thermal ablation as an alternative to surgical resection for selected patients with PTC, there is still no recommended treatment approach for PTCI to date [\u003cspan additionalcitationids=\"CR26 CR27 CR28 CR29 CR30 CR31 CR32\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. There are many controversies among scholars regarding the treatment of PTCI. No reliable conclusions have been drawn due to the underrepresentation of the sample in the small number of relevant clinical studies. Despite the increasing acceptance of RFA as a pre-surgery treatment of low-risk PTC worldwide, RFA is not recommended in China for PTC in the isthmus [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Hence, we retrospectively evaluated the efficacy (assessed by tumor volume reduction rate, tumor complete disappearance rate and disease progression) and safety (assessed by incidence of complications) of ultrasound-guided radiofrequency ablation (RFA) for unifocal T1aN0M0 PTC using sustained, large-sample data. We also compared the data of patients with PTCI and with PTCL during the same period to more accurately evaluate whether ultrasound-guided RFA can be a reliable treatment option for selected patients with PTCI.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e This retrospective study was approved by the Ethics Committee of Hangzhou Weja Hospital. Written informed consent was obtained from each patient prior to the implementation of RFA.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eDefinition of PTCI\u003c/h2\u003e \u003cp\u003eSurgical anatomy defines the isthmus as the band-shape tissue which is located anterior to the trachea and connects the left and right thyroid lobes [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], but there are no clear boundaries for its two sides. The isthmus under ultrasound is defined as the tissue between the two virtual lines on the thyroid gland perpendicular to the outermost bilateral boundaries of the trachea [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. As suggested by Lim et al. [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], we draw two vertical lines perpendicularly from the outermost points of the trachea on both sides to the skin according to the results of a preoperative color ultrasound evaluation of the thyroid and neck lymph node. The central point of a tumor was designated as the intersection point of its longest and shortest diameters. If the central point of the tumor was located between the two virtual lines, the tumor was considered to be located in the isthmus. Fine-needle aspiration (FNA) was performed in view of its advantages in preoperative diagnostic evaluation of thyroid tumors and neck lymph node metastasis including minor trauma, high safety, high diagnostic accuracy and good reproducibility [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, we defined the tumor with its central point between the two virtual lines and confirmed by FNA to be PTC as papillary thyroid carcinoma in the isthmus (PTCI).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ePatients\u003c/h2\u003e \u003cp\u003eWe selected patients with unifocal T1aN0M0 PTC defined by The American Joint Committee on Cancer TNM staging system for DTC [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e], which categorizes T1 differentiated thyroid carcinoma (DTC, maximum tumor diameter\u0026thinsp;\u0026le;\u0026thinsp;20mm) into T1a (maximum tumor diameter\u0026thinsp;\u0026le;\u0026thinsp;10mm) and T1b (10mm\u0026lt;maximum tumor diameter\u0026thinsp;\u0026le;\u0026thinsp;20mm), from all the PTC patients who underwent RFA in Hangzhou Weja Hospital from March 2019 to March 2023. In this definition, N0 suggests no regional lymph node metastasis and M0 suggests no distant metastasis. The patients selected were divided by location of the lesion into the PTCI group (consisting of patients with unifocal T1aN0M0 PTC in the isthmus) and the PTCL group (consisting of patients with unifocal T1aN0M0 PTC in the lobe) for comparative analysis.\u003c/p\u003e \u003cp\u003eThe inclusion criteria were: 1) Patients revealed by ultrasound to have an appropriate route for FNA; 2) Patients confirmed by ultrasound-guided FNA to have PTC; 3) Patients with unifocal T1aN0M0 PTC within the thyroid gland; 4) Patients who had anxiety about the existence of the tumor in their body, refused active surveillance and surgical treatment, and required to receive ablation treatment; 5) Patients who have been followed up no less than 12 months after RFA; 6) Patients who accepted the anonymous use of their data for clinical research. The exclusion criteria were: 1) Patients with evidence of lymph node metastasis; 2) Patients with evidence of distant metastasis; 3) Patients with evidence of capsule contact/invasion or extrathyroidal extension; 4) Patients with severe coagulation mechanism disorders; 5) Patients with dysfunction or failure of important organs (e.g. brain, heart, liver and kidney). Finally, we included 431 patients in this study.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eInstruments and equipment\u003c/h2\u003e \u003cp\u003eWe used Voko color Doppler ultrasound diagnostic instrument and L741 high-frequency linear-array probe, and set the probe frequency to 12MHz. We chose Type L-121 disposable RFA needles and MedSphere radiofrequency therapy instrument (produced by MedSphere International, Inc.) for the implementation of RFA, with the frequency set to 400KHz.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003ePre-RFA assessment\u003c/h2\u003e \u003cp\u003eUltrasound-guided assessment was conducted on each tumor prior to RFA to examine its three orthogonal diameters (i.e. the maximum diameter and the other two perpendicular diameters), position, shape (height/width), calcification, echo, contour, vascular density, internal structure and anatomical adjacency. Each patient underwent full-range examinations including imaging, coagulation function, thyroid function, and complete blood count examinations before RFA. If the PTCI lesion clung to the trachea, normal saline was injected for hydro-dissection during preoperative FNA to test whether the lesion can be successfully completely separated from the trachea. According to the Hydro-dissection Trial (HDT) Theory proposed by Weja Hospital, only the PTCI lesions that can be successfully completely separated from the trachea are eligible for RFA. All the patients were informed of the rationale, procedure, precautions, and possible complications of RFA, and signed an informed consent prior to RFA.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eRFA procedure\u003c/h2\u003e \u003cp\u003eRFA was performed by experienced surgeons proficient in using ultrasound equipment, ultrasound-guided puncture technology, hydro-dissection technology and RFA instrument. The patient was positioned supine. The shoulders were elevated to completely expose the neck. Routine disinfection and draping were performed on the neck. Local anesthesia was performed by injecting 2% lidocaine under ultrasound guidance. For the patients whose lesion was close to the trachea, recurrent laryngeal nerve, esophagus or carotid artery, a hydro-isolation zone was formed by injecting an appropriate amount of hydro-dissection material (i.e. normal saline, 5% glucose, sodium hyaluronate gel, or 5% glucose \u0026amp; sodium hyaluronate gel) once or more times with a 23-gauge needle to keep a distance\u0026thinsp;\u0026gt;\u0026thinsp;5mm between the lesion and adjacent tissues and organs (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). It should be noted that for patients with diabetes, normal saline was used for hydro-isolation as recommended in \"Expert consensus on thermal ablation for thyroid benign nodes, microcarcinoma and metastatic cervical lymph nodes (2018 edition)\" [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The radiofrequency therapy instrument was adjusted to have an output power of 15W. Under ultrasound guidance, the 18G electrode was inserted deepest into the lesion and positioned appropriately. Next, the treatment started using the \"pull-back\" technique and the moving shot technique via the isthmus. Expanded ablation at least 2 mm beyond the boundary of the original lesion was used to avoid lesion residue or recurrence. The treatment ended when a transient hyperechoic zone completely covered the lesion. The ablated tissue was examined by contrast-enhanced ultrasound (CEUS) immediately after RFA to determine whether the lesion was completed ablated. If there was contrast perfusion into the ablated tissue, supplementary RFA was performed immediately to eliminate any residual lesion.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePost-RFA evaluation and follow-up\u003c/h2\u003e \u003cp\u003eAfter RFA, each patient underwent 1\u0026ndash;2 hour observation in the treatment room. Their physical conditions and potential complications were closely monitored and recorded. They were discharged after another 3\u0026ndash;5 hour continuous observation in case of no abnormalities. After RFA, the patients underwent regular follow-ups at 1, 3, 6, 12, 18, 24 months and 12 months thereafter. Ultrasound-guided thyroid and functional examinations were performed to evaluate the following indicators: 1) Volume of the ablated tissue (V), calculated as V (mm\u0026sup3;)\u0026thinsp;=\u0026thinsp;abcπ/6 (a is the maximum diameter, while b and c are the other two diameters perpendicular to a) [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e; \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) Volume reduction rate (VRR), calculated as VRR = (initial volume of the tumor - follow-up volume of the ablated tissue)/initial volume of the tumor\u0026times;100% [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]; 3) Complete disappearance rate (CDR), calculated as CDR\u0026thinsp;=\u0026thinsp;number of cases of complete absorption followed-up/total number of patients followed-up\u0026lowast;100%, where the ablated tissue changing to a linear scar was considered to indicate complete absorption; 4) Number of cases of lymph node metastasis, new occurrence and local recurrence confirmed to be PTC by ultrasound-guided FNA of suspicious nodules that were evaluated by thyroid and neck lymph node ultrasound; 5) number of cases of distant metastasis revealed by Computed Tomography (CT) or Positron Emission Tomography-Computed Tomography (PET-CT) at every two years after RFA or in case of suspicious symptoms; 5) Number of deaths caused by recurrent or metastatic PTC.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eStatistical processing\u003c/h2\u003e \u003cp\u003eThe data collected were analyzed and compared using SPSS software (SPSS for Windows 21.0). The categorical data were expressed in numbers and percentages and compared using chi-square test. The quantitative data that conformed to normal distribution and homogeneity of variance were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) and compared using independent sample t-test. The data of volume before and after RFA were compared using paired sample t-test. For all comparisons, a difference with \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePre-RFA outcomes\u003c/h2\u003e \u003cp\u003eWe included a total of 431 patients who underwent ultrasound-guided RFA for unifocal T1aN0M0 PTC at Hangzhou Weja Hospital between March 2019 and March 2023, and divided them into 59 cases in the PTCI group (with the lesion located in the isthmus) and 372 cases in the PTCL group (with the lesion located in the lobe). The cases of PTCI accounted for 13.69% of all the PTC cases included, slightly higher than the data reported previously [\u003cspan additionalcitationids=\"CR20 CR21\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. This minor deviation may be due to the inclusion of only unifocal T1aN0M0 PTC in this study rather than all types of PTC. The baseline pre-FRA outcomes of the two groups are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The two groups had no statistically significant differences in gender, age, maximum diameter, aspect ratio and calcification (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05), indicating their comparability.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePre-RFA outcomes of the two groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTCI(N\u0026thinsp;=\u0026thinsp;59)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePTCL(N\u0026thinsp;=\u0026thinsp;372)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.810\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMale\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7(11.86%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e81(21.77%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eFemale\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e52(88.14%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e291(78.23%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.906\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e\u0026lt;\u0026thinsp;55\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e52(88.14%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e312(83.87%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e\u0026ge;\u0026thinsp;55\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7(11.86%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e60(16.13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMax diameter (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.933\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e\u0026le;5\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e24(40.68%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e167(44.89%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e\u0026gt;5\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35(59.32%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e205(55.11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAspect ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.703\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e\u0026lt;1\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29(49.15%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e117(31.45%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e\u0026ge;1\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30(50.85%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e255(68.55%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalcification\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.998\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eCalcification\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25(42.37%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e158(42.47%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eNo calcification\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e34(57.63%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e214(57.53%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eRFA outcomes\u003c/h2\u003e \u003cp\u003eAccording to Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the PTCI group had a mean age of 43.79\u0026thinsp;\u0026plusmn;\u0026thinsp;12.04 years, while the PTCL group had a mean age of 43.42\u0026thinsp;\u0026plusmn;\u0026thinsp;10.87 years, with no statistically significant difference (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.809). The PTCI group had a maximum diameter of 5.64\u0026thinsp;\u0026plusmn;\u0026thinsp;1.62mm before RFA, while the PTCL group had a maximum diameter of 5.73\u0026thinsp;\u0026plusmn;\u0026thinsp;2.03mm, with no statistically significant difference (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.733). The PTCI group had a tumor volume of 65.4\u0026thinsp;\u0026plusmn;\u0026thinsp;69.79mm\u0026sup3; before RFA, slightly lower than that of the PTCL group (86.38\u0026thinsp;\u0026plusmn;\u0026thinsp;87.09mm\u0026sup3;), but the difference was not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.079). The ablation time of the PTCI group was 151.92\u0026thinsp;\u0026plusmn;\u0026thinsp;134.77s, slightly higher than that of the PTCL group (120.93\u0026thinsp;\u0026plusmn;\u0026thinsp;122.51s), but the difference was not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.076). The ablation power was 23.36\u0026thinsp;\u0026plusmn;\u0026thinsp;9.62w in the PTCI group and 22.12\u0026thinsp;\u0026plusmn;\u0026thinsp;9.08w in the PTCL group, with no statistically significant difference (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.334). The follow-up period was 31.12\u0026thinsp;\u0026plusmn;\u0026thinsp;12.5 months in the PTCI group, and 28.59\u0026thinsp;\u0026plusmn;\u0026thinsp;11.03 months in the PTCL group, with no statistically significant difference (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.112). The results in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e show that the two groups had no statistically significant differences in pre-RFA tumor size, RFA-related indicators and follow-up period (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRFA outcomes of the two groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003ePTCI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e \u003cp\u003ePTCL\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e43.79\u0026thinsp;\u0026plusmn;\u0026thinsp;12.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e43.42\u0026thinsp;\u0026plusmn;\u0026thinsp;10.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.809\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePre-RFA max diameter (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e5.64\u0026thinsp;\u0026plusmn;\u0026thinsp;1.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e5.73\u0026thinsp;\u0026plusmn;\u0026thinsp;2.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.733\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePre-RFA volume (mm\u0026sup3;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e427.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e65.4\u0026thinsp;\u0026plusmn;\u0026thinsp;69.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e471.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e86.38\u0026thinsp;\u0026plusmn;\u0026thinsp;87.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.079\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAblation time (s)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e151.92\u0026thinsp;\u0026plusmn;\u0026thinsp;134.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e120.93\u0026thinsp;\u0026plusmn;\u0026thinsp;122.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.076\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAblation power (w)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e23.36\u0026thinsp;\u0026plusmn;\u0026thinsp;9.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e22.12\u0026thinsp;\u0026plusmn;\u0026thinsp;9.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.334\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFollow-up period (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e31.12\u0026thinsp;\u0026plusmn;\u0026thinsp;12.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e28.59\u0026thinsp;\u0026plusmn;\u0026thinsp;11.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.112\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003ePost-RFA outcomes\u003c/h2\u003e \u003cp\u003eTables\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026thinsp;\u0026minus;\u0026thinsp;1 and 3\u0026thinsp;\u0026minus;\u0026thinsp;2 show the ablated tissue volume, VRR, and CDR of the two groups at 1 (M1), 3 (M3), 6 (M6), 12 (M12), 18 (M18), 24 (M24), 36 (M36) and 48 months (M48) after RFA. According to Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026thinsp;\u0026minus;\u0026thinsp;1, the volume of the PTCI group was 288.67\u0026thinsp;\u0026plusmn;\u0026thinsp;210.48mm\u0026sup3;at M1, significantly larger than the tumor volume (65.4\u0026thinsp;\u0026plusmn;\u0026thinsp;69.79mm\u0026sup3;), showing a statistically significant difference (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Because of expanded ablation, the ablation tissue was much larger than the original tumor in size. The part absorbed 1 month after RFA was still much smaller than the tissue outside the original tumor that was ablated. The volume of the PTCI group was 108.42\u0026thinsp;\u0026plusmn;\u0026thinsp;122.02mm\u0026sup3; at M3, slightly higher than the initial volume, but the difference was not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.086), indicating that the ablated tissue gradually decreased in size and approached the original tumor volume as time progressed. From M6, the volume was significantly smaller than the initial volume, and the differences were statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05): it was 30.68\u0026thinsp;\u0026plusmn;\u0026thinsp;45.56mm\u0026sup3; at M6, 2.75\u0026thinsp;\u0026plusmn;\u0026thinsp;7.01mm\u0026sup3; at M12, 0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;1.46mm\u0026sup3; at M18, 0.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98mm\u0026sup3; at M24, and 0mm\u0026sup3;at M36 and M48.\u003c/p\u003e \u003cp\u003eAccording to Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026thinsp;\u0026minus;\u0026thinsp;1, the VRR of the PTCI group was \u0026minus;\u0026thinsp;618.62\u0026thinsp;\u0026plusmn;\u0026thinsp;655.61% and \u0026minus;\u0026thinsp;127.68\u0026thinsp;\u0026plusmn;\u0026thinsp;257.35% respectively at M1 and M3, both negative because the ablated tissue was still greater than the initial tumor in size before 3 months. From M6, the ablated tissue was smaller than the initial tumor, so that the VRR turned positive and gradually increased: it was 39.64\u0026thinsp;\u0026plusmn;\u0026thinsp;117.48% at M6, and significantly increased to 95.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.78% at M12, 98.9\u0026thinsp;\u0026plusmn;\u0026thinsp;5.16% at M18, 99.28\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44% at M24, and 100% at M36 and M48. The CDR was 1.69% at M1, 11.86% at M3, 40.68% at M6, 74.58% at M12, 93.62% at M18, 94.44% at M24, and 100% at M36 and M48.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u0026thinsp;\u0026minus;\u0026thinsp;1 Post-RFA volume, VRR and CDR of the PTCI group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTime point\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eV(mm\u0026sup3;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e \u003cp\u003eVRR(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003eCDR\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eCases\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eCDR(%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e758.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e288.67\u0026thinsp;\u0026plusmn;\u0026thinsp;210.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-2016.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e-618.62\u0026thinsp;\u0026plusmn;\u0026thinsp;655.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1/59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.69\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e572.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e108.42\u0026thinsp;\u0026plusmn;\u0026thinsp;122.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.086\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1136.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e-127.68\u0026thinsp;\u0026plusmn;\u0026thinsp;257.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e7/59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e11.86\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e143.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e30.68\u0026thinsp;\u0026plusmn;\u0026thinsp;45.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-462.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e39.64\u0026thinsp;\u0026plusmn;\u0026thinsp;117.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e24/59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e40.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.75\u0026thinsp;\u0026plusmn;\u0026thinsp;7.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e43.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e95.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e45/59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e74.58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;1.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e75.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e98.9\u0026thinsp;\u0026plusmn;\u0026thinsp;5.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e44/47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e93.62\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e83.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e99.28\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e34/36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e94.44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e100\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e21/21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e100\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e6/6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"11\"\u003eNote: \u003cem\u003eP\u003c/em\u003e in this table was a statistical result of comparison between the ablated tissue volume at each follow-up time point and the initial volume before RFA.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAccording to Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026thinsp;\u0026minus;\u0026thinsp;2, the volume change trend of the PTCL group was roughly similar to that of the PTCI group. The ablated tissue was significantly larger than the initial tumor in size at M1, and the difference was statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). From M6, the ablated tissue was significantly smaller than the initial tumor in size, and the differences were statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The first dissimilarity between the two groups in tumor volume change was found at M3: the volume of the PTCI group was slightly higher than the initial volume, and the difference was not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0860), whereas the volume of the PTCL group was significantly higher than the initial volume, and the difference was statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). This should be attributed to the narrow space in the isthmus which limited the scope for ablation expansion. Probably for this reason, the volume of the PTCI group was basically smaller than that of the PTCL group, as shown in Table\u0026nbsp;\u0026lt;link rid=\"tb5\"\u0026gt;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u0026lt;/link\u0026gt;\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Besides, the ablated tissue was completely absorbed earlier in the PTCI group than in the PTCL group. The changes in VRR and CDR in the PTCL group were similar to those in the PTCI group.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u0026thinsp;\u0026minus;\u0026thinsp;2 Post-RFA volume, VRR and CDR of the PTCL group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTime point\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eV(mm\u0026sup3;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e \u003cp\u003eVRR(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003eCDR\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eCases\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eCDR(%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2027.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e415.55\u0026thinsp;\u0026plusmn;\u0026thinsp;359.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-8576.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e-789.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1135.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e6/372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.61\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1049.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e144.96\u0026thinsp;\u0026plusmn;\u0026thinsp;193.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-3602.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e-188.74\u0026thinsp;\u0026plusmn;\u0026thinsp;486.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e30/372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e8.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e775.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e45.78\u0026thinsp;\u0026plusmn;\u0026thinsp;85.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1542.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e0.53\u0026thinsp;\u0026plusmn;\u0026thinsp;225.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e118/372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e31.72\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e276.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e11.71\u0026thinsp;\u0026plusmn;\u0026thinsp;35.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-133.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e84.09\u0026thinsp;\u0026plusmn;\u0026thinsp;39.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e250/372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e67.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e133.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.95\u0026thinsp;\u0026plusmn;\u0026thinsp;13.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-30.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e94.34\u0026thinsp;\u0026plusmn;\u0026thinsp;19.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e265/297\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e89.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e95.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.24\u0026thinsp;\u0026plusmn;\u0026thinsp;10.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e96.04\u0026thinsp;\u0026plusmn;\u0026thinsp;14.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e198/212\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e93.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.67\u0026thinsp;\u0026plusmn;\u0026thinsp;3.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e81.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e99.11\u0026thinsp;\u0026plusmn;\u0026thinsp;3.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e90/93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e96.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e \u003cp\u003e100\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e18/18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"11\"\u003eNote: \u003cem\u003eP\u003c/em\u003e in this table was a statistical result of comparison between the ablated tissue volume at each follow-up time point and the initial volume before RFA.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u0026lt;link rid=\"tb5\"\u0026gt;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u0026lt;/link\u0026gt;\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the results of comparison between the two groups in volume, VRR, and CDR after RFA. At M1, the volume of the PTCI group was significantly lower than that of the PTCI group, and the difference was statistically significant \u003cem\u003e(P\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). This can be attributed to the smaller scope for expanded ablation in the PTCI group due to the small size of the isthmus to avoid thermally damaging adjacent tissues and organs. Except for a significant difference in volume at M1, the volume of the PTCI group was slightly lower than that of the PTCL group at all the follow-up time points between 6 and 36 months, but the differences were not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). As for VRR, at all the follow-up time points between 1\u0026ndash;36 months, the PTCI group had a higher VRR than the PTCL group, but the differences were not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The same trend occurred in the changes in CDR: at all the follow-up time points between 1\u0026ndash;36 months, the CDR of the PTCI group was higher than that of the PTCL group, but the differences were not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). At M48, the two groups were identical in volume, VRR, and CDR.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e3 Comparison of the two groups in Post-RFA volume, VRR and CDR\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTime point\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eV(mm\u0026sup3;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eVRR(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003eCDR(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTCI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePTCL\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePTCI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePTCL\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003ePTCI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003ePTCL\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.603\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e288.67\u0026thinsp;\u0026plusmn;\u0026thinsp;210.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e417.93\u0026thinsp;\u0026plusmn;\u0026thinsp;368.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.035\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e-618.62\u0026thinsp;\u0026plusmn;\u0026thinsp;655.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e-789.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1135.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.337\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e108.42\u0026thinsp;\u0026plusmn;\u0026thinsp;122.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e144.96\u0026thinsp;\u0026plusmn;\u0026thinsp;193.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.264\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e-127.68\u0026thinsp;\u0026plusmn;\u0026thinsp;257.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e-188.74\u0026thinsp;\u0026plusmn;\u0026thinsp;486.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.491\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e11.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e8.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e30.68\u0026thinsp;\u0026plusmn;\u0026thinsp;45.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e45.78\u0026thinsp;\u0026plusmn;\u0026thinsp;85.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.345\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e39.64\u0026thinsp;\u0026plusmn;\u0026thinsp;117.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e0.53\u0026thinsp;\u0026plusmn;\u0026thinsp;225.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.383\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e40.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e31.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.75\u0026thinsp;\u0026plusmn;\u0026thinsp;7.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e11.71\u0026thinsp;\u0026plusmn;\u0026thinsp;35.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.146\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e95.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e84.09\u0026thinsp;\u0026plusmn;\u0026thinsp;39.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.082\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e74.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e67.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;1.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.95\u0026thinsp;\u0026plusmn;\u0026thinsp;13.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.354\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e98.9\u0026thinsp;\u0026plusmn;\u0026thinsp;5.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e94.34\u0026thinsp;\u0026plusmn;\u0026thinsp;19.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e93.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e89.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.24\u0026thinsp;\u0026plusmn;\u0026thinsp;10.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.338\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e99.28\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e96.04\u0026thinsp;\u0026plusmn;\u0026thinsp;14.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.303\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e94.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e93.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.67\u0026thinsp;\u0026plusmn;\u0026thinsp;3.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.437\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e100\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e99.11\u0026thinsp;\u0026plusmn;\u0026thinsp;3.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.352\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e96.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e100\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e \u003cp\u003e100\u0026thinsp;\u0026plusmn;\u0026thinsp;0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows hydro-dissection, incidence of complications, and disease progression after RFA in the two groups. 5% glucose and 5% glucose \u0026amp; sodium hyaluronate gel were used for hydro-dissection more frequently in both groups. The PTCI group did not have any complications, while the PTCL group had a total of 7 complications (1.88%), including 4 cases of hoarseness or hoarseness (recovering within 3 months after RFA without treatment) and 3 cases of coughing during drinking water (recovering within 1\u0026ndash;4 weeks after RFA without treatment). Regarding disease progression, neither group was found to have lymph node metastasis, distant metastasis, new tumors, local recurrence, or death caused by PTC during the follow-up period.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eHydro-dissection, complications and disease progression in the two groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTCI(N\u0026thinsp;=\u0026thinsp;59)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePTCL(N\u0026thinsp;=\u0026thinsp;372)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHydro-dissection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59(100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e358(96.24)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eNormal saline\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5(8.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7(1.88)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e5% glucose\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26(44.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e309(83.07)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eSodium hyaluronate gel\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3(5.08)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2(0.54)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e5% glucose \u0026amp; sodium hyaluronate gel\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25(42.37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40(10.75)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eNo\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14(3.76)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplication\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7(1.88)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eThickening or hoarseness of voice\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4(1.08)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eCoughing during drinking water\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3(0.08)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eDysphagia\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eBleeding or infection\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eTracheal or esophageal injury\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePermanent recurrent laryngeal nerve injury\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eParathyroid injury\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eThyroid dysfunction\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDisease progression\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eLymph node metastasis\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eDistant metastasis\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eNew tumor\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eLocal recurrence\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eDeaths caused by PTC\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe results of our cohort study confirm the effectiveness and safety of RFA as a treatment option for unifocal T1aN0M0 PTC in the isthmus. The results show basically no differences between the PTCI group and the PTCL group in volume change, VRR, CDR, incidence of complications and disease progression. Specifically, the VRR and the CDR of the PTCI group were slightly higher than those of the PTCL group at all the time points within 36 months. All the PTCI lesions were fully absorbed up to 36 months, and all the PTCL lesions were fully absorbed up to 48 months, without disease progression during the follow-up period. The PTCI group did not have any compilations, while the PTCL group had a total of 7 compilations (1.88%).\u003c/p\u003e \u003cp\u003eIn a comparative study of 181 PTCI cases and 1792 PTCL cases, Lee et al. argued that total thyroidectomy should also be performed during initial treatment based on their findings that PTCI was more likely to invade the capsule and have multifocal lesions at an early stage and that PTCI had higher incidence of lymph node metastasis in zone VI and lower incidence of lateral lymph node metastasis [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Nixon et al. analyzed 19 PTCI cases and recommended isthmusectomy as a treatment option for low-risk PTCI because it did not affect the patient's survival rate and also protected the recurrent laryngeal nerve and parathyroid gland from injury [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Although lobectomy has been recommended as a less radical alterative to total thyroidectomy for PTC limited to a single lobe and detected at an early stage, no clear therapeutic strategy for PTC restricted in the isthmus is found in the guidelines [\u003cspan additionalcitationids=\"CR26 CR27 CR28 CR29 CR30 CR31 CR32\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMost T1aN0M0 PTC tumors were found to remain indolent, clinically silent and small over time, and delayed surgery was performed only when disease progression was detected during the surveillance of node metastasis or tumor growth [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. For this reason, active surveillance has been proposed as a tailored approach for the management of T1aN0M0 PTC. This targeted approach was initiated by Kuma Hospital in 1993 as an alternative to immediate surgery and aggressive treatment in the context of overtreatment [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Kuma Hospital conducted a series of long-term observation trials [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], with the longest one lasting for 30 years [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and reported extremely low rates of tumor size enlargement and new cases of node metastasis during 10-year, 22-year and 30 year follow-ups to support their proposal of active surveillance. In their latest observation, they found\u0026thinsp;\u0026ge;\u0026thinsp;3mm tumor size enlargement only in 3.8% patients who underwent active surveillance, tumor size enlargement in 4.7% and 6.6% active surveillance cases respectively in 10 years and 20 years, novel lymph node metastases in 0.8% active surveillance cases, no deaths caused by TC, and no significant clinical differences between low-risk PTC patients who underwent immediate surgery and underwent active surveillance [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. During the roughly same period, Cancer Institute Hospital carried out a 5-year (ranging from 1 to 17 years) observation of 300 patients with low-risk asymptomatic PTC and found tumor size enlargement in only 7% patients, occurrence of lymph node metastases in 1% patients, and no new occurrence of distant metastases or extrathyroidal extension [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThese favorable outcomes of active surveillance clearly demonstrate that surgery is necessary only for an extremely small proportion of patients with low-risk PTC. From the perspective of the patient's survival rate, the implementation of surgery for selected patients detected to have disease progression during the observation period is deemed to be as effective as immediate surgical resection. Hence, periodic follow-up has been recommended as an option superior to immediate surgery for T1aN0M0 PTC in view of its good prognosis [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. However, the natural history of more aggressive PTC tumors with lymph node metastasis and distant metastasis detected during initial screening or early follow-up should be better understood to determine the optimal management strategy [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the feasibility of active surveillance for T1aN0M0 PTC, some patients have varying degrees of anxiety and unease about the existence of PTC in their body. Most patients are more willing to accept relatively positive intervention measures rather than just active surveillance. In view of the essential function of active surveillance in mitigating the overtreatment of low-risk PTC featured with an indolent nature, local ablative therapies which are not potentially harmful but useful and reasonably priced may be a less invasive means to treat TC in patients who are unable or refuse to accept their cancer untreated, but they should not replace necessary resection therapies [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Ultrasound-guided thermal ablation has been confirmed by a large number of studies to be effective and safe for T1aN0M0 PTC and has been widely used in clinical practice for the treatment of T1aN0M0 PTC [\u003cspan additionalcitationids=\"CR45 CR46 CR47\" citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs pointed out by Chinese Ultra Sound Doctors Association, thermal ablation is easy to operate, precise in positioning, safe and effective in inactivating the tumor before disease progression to alleviate patients' psychological pressure [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. The consensus released by Chinese Ultra Sound Doctors Association specifies the indications and contraindications of using thermal ablation to treat T1aN0M0 PTC, and provides a detailed, complete explanation of the preoperative diagnosis of T1aN0M0 PTC [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. A number of guidelines and consensuses given by multiple associations also mention that for T1aN0M0 PTC discovered by chance, thermal ablation is a potential alternative to active surveillance and immediate surgical resection provided that the patient refuses or is not qualified for surgery, and is unwilling to undergo active surveillance [\u003cspan additionalcitationids=\"CR26 CR27 CR28 CR29 CR30\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. In \"Expert consensus on thermal ablation of papillary thyroid cancer (2024 edition)\", the latest PTC-targeted consensus jointly released by several leading associations and committees in China based on a large number of convincing empirical results, thermal ablation is highly recommended as one of the first-line treatment methods for T1aN0M0 PTC in view of its similar treatment outcomes to surgical resection and its evidence-supported advantages over surgical resection including minimal invasiveness, low incidence of complications, no need to accept lifelong hormone replenishment, short operative time, fast postoperative recovery, and high quality of life after RFA [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRadiofrequency ablation (RFA), in virtue of its minimal invasiveness, predictable, safe and easy procedure, low incidence of complications, and high-quality postoperative life, has been recommended in recent years as a potential remedy option for benign thyroid nodules and TC [\u003cspan additionalcitationids=\"CR48 CR49\" citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. Its effectiveness in treating unifocal PTCI was also confirmed in a retrospective study by General Hospital of Chinese PLA, where it was found that all the lesions performed with ultrasound-guided RFA were successfully ablated and completely disappeared at 18 months without any complications, lymph node metastasis and abnormal thyroid function and that the VRR was 97.6\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2% and 99.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8%, respectively at 6 months and 12 months [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, the application of RFA in malignant thyroid tumors is still controversial [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]. In a clinical analysis of 5 patients who underwent surgery after RFA, it was found that non-standard implementation of RFA caused anatomical boundary ambiguity and local tissue adhesion, which increased difficulty in following surgical operation [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]. The reason was attributed to unfamiliarity with tumor biological behavior and anatomy. To ensure successful RFA treatment and minimize potential complications, the operator is required to be familiar with thyroid anatomy and ultrasound images, proficient in using RFA-related instruments and equipment, and skilled in avoiding potential complications [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]. Besides, the use of hydro-dissection materials during RFA is an important way to protect adjacent tissues and other important structures. \"Expert consensus on thermal ablation of thyroid cancer (2024 edition)\" also highlights the requirements on operators, including obtaining relevant qualifications, proficient ultrasound examination and image recognition, proficient puncture techniques, proficient hydro-dissection techniques, proficient use of thermal ablation instruments, and rich experience in thermal ablation of benign thyroid tumors [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe 0 incidence of complications in the PTCI group may be partially attributed to the implementation of Hydro-dissection Trial (HDT) during FNA, which functioned in ensuring that PTCI lesions can be successfully completely separated from the trachea. We ascribe these favorable outcomes to the effectiveness and safety of RFA, the selection of unifocal T1aN0M0 PTC cases, the implementation of HDT during FNA initiated by Hangzhou Weja Hospital in selected PTCI cases, and the proficiency of the RFA operator.\u003c/p\u003e \u003cp\u003eHowever, our study has certain limitations. Firstly, the data were collected from a single center, suggesting the need for multicenter results to support the conclusions drawn here. Secondly, the follow-up period is not long enough to evaluate disease progression that may occur when the observation time is extended. Thirdly, we did not evaluate whether RFA has a similar effect in treating multifocal T1aN0M0 PTC. Fourthly, we did not evaluate whether RFA increases the difficulty of subsequent surgical operation in the case of disease progression since no participant was performed with surgery after RFA.\u003c/p\u003e \u003cp\u003eIn conclusion, the results of our study indicate that RFA is a reliable treatment option for unifocal T1aN0M0 PTC, either in the lobe or in the isthmus, in view of its effectiveness in slowing down tumor progression or outward metastasis and its high safety demonstrated by our large-sample data. We recommend the setting of strict inclusion criteria for patients selected to perform RFA, the implementation of HDT during FNA, and the training of proficient RFA operators to ensure the reliability of RFA in treating PTC.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDr. Gongli Zhou, who is president of Hangzhou Weja Hospital, envisioned the prospect of research into fields related to thyroid and has been insisting on engaging patients in follow-ups to collect their data since the establishment of the hospital. This study would not have been possible without his permission and support. The authors gratefully acknowledge the assistance provided by staff at Hangzhou Weja Hospital and the instructive support from Chinese Academy of Sciences.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZ. G. and X. D. performed conceptualization, data curation, methodology, project administration, supervision and review. Z. B. took charge of formal analysis, investigation and resources. S. R. performed data curation, visualization and writing. X. K. and Z. X. performed formal analysis, investigation and editing. L. F., Z. W and C. T. took charge of recourses, software and visualization.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe output data used to support the findings of this study are included within the article. The detailed patient data used to support the findings of this study are restricted by the Ethics Committee of Hangzhou Weja Hospital in order to protect PATIENT PRIVACY. Data are available from Gongli Zhou ([email protected]) for researchers who meet the criteria for access to confidential data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo commercial interest or funding is involved in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis retrospective study was approved by the Ethics Committee of Hangzhou Weja Hospital (No. 2024004) and was completed in accordance with the revised guidelines of the Declaration of Helsinki (2013). Written informed consent was obtained from each patient prior to the implementation of RFA. Registry and the Registration No. of the study/trial: N/A; Animal Studies: N/A.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eFerlay, J. \u003cem\u003eet al\u003c/em\u003e. Estimating the global cancer incidence and mortality in 2018: Globocan sources and methods.\u003cem\u003e International Journal of Cancer\u003c/em\u003e \u003cstrong\u003e144\u003c/strong\u003e, 1941-1953 (2019).\u003c/li\u003e\n\u003cli\u003eNational Cancer Institute. SEER cancer statistics review, 1975-2014. SEER Statistics, 2018. Preprint at https://seer.cancer.gov/archive/csr/1975_2014/ (2018).\u003c/li\u003e\n\u003cli\u003eTopstad, D. \u0026amp; Dickinson, J. A. Thyroid cancer incidence in Canada: a national cancer registry analysis. \u003cem\u003eCMAJ Open\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, E612-E616 (2017).\u003c/li\u003e\n\u003cli\u003eWang, J., Yu, F., Shang, Y., Ping, Z. \u0026amp; Liu, L. 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The efficacy of ultrasound-guided RFA was evaluated by volume reduction rate (VRR), complete disappearance rate (CDR), and disease progression, and the safety was evaluated by incidence of complications. The two groups exhibited a consistent trend of change, with the PTCI group performing slightly better in volume, VRR, and CDR at all follow-up time points expect 1 month. The mean initial volume of the PTCI group vs the PTCL group decreased significantly from 65.4\u0026thinsp;\u0026plusmn;\u0026thinsp;69.79 vs 86.38\u0026thinsp;\u0026plusmn;\u0026thinsp;87.09mm\u0026sup3; (range 10.92-427.58 vs 3.05-471.6mm\u0026sup3;) to 0 vs 0 mm\u0026sup3; at a mean follow-up time of 31.12\u0026thinsp;\u0026plusmn;\u0026thinsp;12.5 months (range 12\u0026ndash;60 months); their VRR increased significantly from \u0026minus;\u0026thinsp;618.62\u0026thinsp;\u0026plusmn;\u0026thinsp;655.61% vs -789.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1135.07%, at 1 month to 100% vs 100% at 48 months. No disease progression was found in the two groups. The PTCI group had no complications, whereas the PTCL group had 7 complications (1.88%). Ultrasound-guided RFA is reliable for unifocal T1aN0M0 PTCI in the isthmus.\u003c/p\u003e","manuscriptTitle":"Is ultrasound-guided radiofrequency ablation reliable for unifocal T1aN0M0 papillary thyroid carcinoma in the isthmus: A retrospective cohort study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-11 12:19:54","doi":"10.21203/rs.3.rs-4734711/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"14902add-0550-4424-a247-2c69148b9e9d","owner":[],"postedDate":"August 11th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":35511319,"name":"Biological sciences/Cancer"},{"id":35511320,"name":"Health sciences/Diseases"},{"id":35511321,"name":"Health sciences/Endocrinology"},{"id":35511322,"name":"Health sciences/Oncology"}],"tags":[],"updatedAt":"2024-10-28T11:38:16+00:00","versionOfRecord":[],"versionCreatedAt":"2024-08-11 12:19:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4734711","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4734711","identity":"rs-4734711","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}