Concordance among radiological, laparoscopic and laparotomic peritoneal cancer index assessments in patients undergoing cytoreductive surgery for peritoneal metastases

Concordance among radiological, laparoscopic and laparotomic peritoneal cancer index assessments in patients undergoing cytoreductive surgery for peritoneal metastases | 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 Research Article Concordance among radiological, laparoscopic and laparotomic peritoneal cancer index assessments in patients undergoing cytoreductive surgery for peritoneal metastases Silvia Guerrero-Macías, Vaneza Ávila-Rodríguez, Jorge Andrés Urrutia, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8746936/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Purpose Accurate preoperative estimation of the Peritoneal Cancer Index (PCI) is essential for optimal patient selection and surgical planning in peritoneal metastases. This study aimed to quantify the agreement between preoperative radiological PCI (rPCI) and laparoscopic PCI (lapPCI) compared with intraoperative laparotomic PCI (crsPCI) in patients undergoing cytoreductive surgery (CRS), and to explore the potential implications of PCI discordance for preoperative staging. Methods We conducted a retrospective cohort study including patients who underwent CRS for peritoneal metastases at a tertiary cancer center between August 2023 and February 2025. All patients had preoperative cross-sectional imaging, and a subset underwent diagnostic laparoscopy. Radiological PCI was retrospectively assigned by an experienced radiologist blinded to surgical findings. Agreement between rPCI, lapPCI, and crsPCI was assessed using intraclass correlation coefficients (ICC), Bland–Altman analysis, and correlation statistics. Results Fifty-six patients were included. Preoperative imaging consisted of MRI in 70% and CT in 30% of cases. Laparoscopic PCI was available in 16 patients (28.5%). The mean rPCI was 9.25 (IQR 3–13), compared with a mean crsPCI of 14.23 (IQR 9–18.5). Radiologic assessment showed good agreement with surgical PCI (ICC = 0.82; 95% CI 0.74–0.88), but systematically underestimated disease extent, with a mean bias of + 4.98 PCI units. Laparoscopic PCI demonstrated excellent agreement with crsPCI (ICC = 0.94; 95% CI 0.85–0.98) and minimal bias (− 1.5 PCI units). Correlation analyses supported these findings. Conclusion Radiologic PCI demonstrates good concordance with intraoperative findings but consistently underestimates tumor burden. In contrast, laparoscopic assessment provides excellent agreement with surgical PCI and offers valuable complementary information for preoperative staging. These results support a multimodal staging approach integrating radiologic and laparoscopic evaluation to improve accuracy in patient selection for CRS. Peritoneal Neoplasms Peritoneal Cancer Index Cytoreductive Surgery Diagnostic Imaging Laparoscopy Figures Figure 1 Figure 2 Figure 3 Figure 4 Background Peritoneal metastases (PM) represent a complex and heterogeneous manifestation of advanced abdominal and gynecologic malignancies. In selected patients, the combined use of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) has changed the natural history of PM, offering prolonged survival and, in some cases, long-term disease control. Accurate preoperative staging and quantification of peritoneal disease are therefore essential to select patients who are likely to benefit from this surgical approach while avoiding non-therapeutic laparotomies and unnecessary morbidity 1 , 2 . Jacquet and Sugarbaker introduced a standardized, reproducible system for estimating the extent and distribution of peritoneal carcinomatosis: the Peritoneal Cancer Index (PCI). The PCI divides the abdominal cavity into 13 regions and assigns a lesion-size score in each region, producing a value (0–39) that reflects overall tumor burden. The surgical PCI remains one of the most important prognostic indicators for patients considered for CRS, correlating strongly with the probability of achieving complete cytoreduction and with overall survival 3 . Preoperative estimation of PCI is commonly attempted with cross-sectional imaging such as contrast-enhanced computed tomography (CT). However, conventional imaging frequently underestimates tumor burden, particularly in the small bowel and mesenteric regions, with multiple series and meta-analyses reporting systematic underestimation of surgical PCI by CT and variable sensitivity across regions and lesion sizes 4 , 5 . Advanced imaging approaches (MRI with diffusion-weighted imaging, dual-energy CT, and hybrid PET/MRI or novel tracers such as FAPI) are improving detection but limitations persist, especially for small-volume and serosal disease 6 . Diagnostic laparoscopy offers direct visualization of peritoneal surfaces and has been proposed as an intermediate staging tool to complement imaging. Multiple cohorts and prospective series show that diagnostic laparoscopy improves patient selection for CRS-HIPEC and reduces the rate of non-therapeutic laparotomies by detecting unresectable disease that was missed on imaging 7 , 8 . However, laparoscopic PCI has some limitations: peritoneal adhesions, hidden spaces or restricted visualization of some small-bowel surfaces may produce discordance with the subsequent open (laparotomic) assessment. Interobserver variability and the experience of the operator also affect laparoscopic scoring reproducibility 9 . (Table 1 ) Treatment decisions in peritoneal malignancies, particularly the indication of CRS and planned resection extension, depend heavily on accurate preoperative Peritoneal Cancer Index (PCI) estimation. Consequently, determining the level of agreement among radiological, laparoscopic, and laparotomic PCI assessments is fundamental for an optimal patient selection. A better understanding of the concordance of staging models could help in the selection and work-up for these patients adding the laparoscopy or not after imaging tests. Accordingly, this study aims to quantify the agreement between preoperative radiological (rPCI) and laparoscopic (lapPCI) assessments versus the intraoperative laparotomic PCI (crsPCI) in patients underwent CRS for peritoneal metastases, and to explore the potential implications of PCI discordance for preoperative staging and surgical planning in patients undergoing CRS. Table 1 Sensitivity of Different Modalities in Detecting Peritoneal Disease (overall and by region) Modality / Clinical Scenario Overall Sensitivity / Accuracy Region-Specific Performance CT vs Surgical PCI Overall concordance with surgical PCI ~ 30%. CT underestimated PCI in ~ 46% and overestimated in ~ 24% of cases 11 Accuracy varied by region (≈ 60–80%). Upper abdominal regions (PCI 1–3): ~60–70%. Small bowel regions (PCI 9–12): ~60–80%, with frequent underestimation of disease extent 11 Radiologic PCI (CT and FDG-PET) in Repeat CRS/HIPEC Overall sensitivity ~ 30.8%; specificity ~ 79.9% for radiologic PCI 12 High sensitivity in pelvic regions (~ 80–87.5%). Very low sensitivity in epigastric regions (0–25%) and small bowel regions (25–33%) for both CT and FDG-PET 12 MRI vs CT for Detection of Peritoneal Surface Malignancies MRI: ~49.1%; CT: ~47.8% (averaged across all PCI regions). 13 Small bowel regions (PCI 9–12): MRI ~ 19–31%, CT ~ 0–7%. Moderate to good sensitivity (~ 58–79%) in several upper, lower, and flank regions (PCI 1, 3–8). 13 Meta-analysis of Imaging Modalities (CT, PET/CT, DW-MRI) CT: ~68%; PET/CT: ~80%; DW-MRI: ~92% (overall sensitivity for peritoneal metastasis detection). 15 Region-based analysis shows reduced sensitivity of CT in small bowel regions. CT region-based specificity ~ 88%. PET/CT and DW-MRI demonstrated superior performance across most regions. 15 Laparoscopy vs Open Exploration (PCI Assessment) Exact PCI concordance ~ 25.6%; underestimation in ~ 62.8%; overestimation in ~ 11.6% of cases. 8 Misestimation more frequent in regions involving small bowel. Accuracy was not influenced by tumor type or prior systemic therapy. 8 CT Accuracy in Predicting Resectability / CRS Feasibility CT sensitivity for predicting complete cytoreduction ~ 35–45%, with limited ability to exclude unresectable disease. 16 Lowest accuracy observed in small bowel and mesenteric regions; better performance in pelvis and paracolic gutters. 16 Methods We conducted a retrospective cohort study including all patients who underwent CRS for peritoneal metastases at Centro de Investigación y Tratamiento del Cáncer Luis Carlos Sarmiento Angulo (CTIC) Foundation, between August 2023 and February 2025. Patients were identified from a prospectively maintained institutional database. Cases were eligible if complete data were available for preoperative imaging, diagnostic laparoscopy, and crsPCI assessment. Patients with incomplete documentation, palliative intent procedures, or non-oncologic peritoneal disease were excluded. This analysis includes only patients who proceeded to CRS; patients deemed unresectable preoperatively were not captured (Fig. 1 ). Radiologic Evaluation All patients underwent CT or MRI of the chest, abdomen, and pelvis as part of the preoperative workup was done. A radiologist with expertise in peritoneal surface malignancies, blinded to surgical and laparoscopic findings, retrospectively reviewed the imaging studies to assign a radiological peritoneal cancer index (rPCI) following the 13-regions distribution and lesion size criteria described by Jacquet and Sugarbaker. Each lesion was scored from 0 to 3 according to the largest nodule size in each region, and the sum provided the total rPCI (0–39). (Fig. 2 ) Laparoscopic Evaluation When diagnostic laparoscopy was performed prior to CRS, operative reports and intraoperative images were reviewed to extract the lapPCI. All laparoscopic procedures were performed by surgeons trained in peritoneal surface malignancies, using a systematic inspection of the 13 abdominopelvic regions. Adhesions or limited visualization were documented. The lapPCI value used for analysis corresponded to the surgeon’s recorded total score at the time of laparoscopy. Open (cytoreductive surgery) assessment The crsPCI, obtained during open cytoreductive surgery, was considered the reference standard. The scoring was performed systematically after complete exploration of all peritoneal regions, before starting cytoreduction. When available, photographic or video documentation was used to confirm regional lesion assignment and improve inter-observer variability. Statistical Analysis Descriptive statistics were used to summarize demographic and clinical variables. Agreement between rPCI, lapPCI, and crsPCI was analyzed using the Bland–Altman method to estimate bias (mean difference) and 95% limits of agreement. The intraclass correlation coefficient (ICC) was calculated to assess overall concordance, with values interpreted as: poor ( 0.9). Pearson’s correlation coefficient was used for linear association of continuous PCI values, while Spearman’s rank correlation assessed ordinal relationships and non-parametric distributions. Additionally, subgroup analyses were conducted according to: Primary tumor origin (colorectal, appendiceal, gastric, ovarian, others), PCI categories (low ≤ 10, intermediate 11–20, high > 20). Differences between modalities were compared using paired-sample t tests or Wilcoxon signed-rank tests as appropriate. Statistical analyses were performed using SPSS version 29.0 (IBM Corp., Armonk, NY, USA) and R version 4.3.1 (R Foundation for Statistical Computing, Vienna, Austria). A two-tailed p value < 0.05 was considered statistically significant. Ethical Considerations The study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the Institutional Review Board. Results A total of 56 patients who underwent cytoreductive surgery for peritoneal metastases between August 2023 and February 2025 were included in the analysis. All patients had preoperative radiologic assessment (rPCI), performed using magnetic resonance imaging (MRI) in 70% and computed tomography (CT) in 30% of cases. Laparoscopic PCI (lapPCI) was available for 16 patients (28.5%), most frequently among those with gastric cancer (80%). The median age was 57 years (IQR 48–64), and the majority were female (83.9%). Ovarian cancer represented the predominant primary tumor (55.3%), followed by gastric (23.2%), pseudomyxoma peritonei (8.9%), colorectal (3.5%), and others (8.9%). Mean body mass index (BMI) was 23.6 kg/m². Complete cytoreduction (CC-0) was achieved in 94% of cases, and HIPEC was performed in 25% (Table 2 ). Radiologic PCI Assessment The mean rPCI was 9.25 (IQR 3–13), compared with a mean surgical PCI (crsPCI) of 14.23 (IQR 9–18.5). Radiologic evaluation showed a good level of agreement with the surgical PCI, with an intraclass correlation coefficient (ICC) of 0.82 (95% CI 0.74–0.88). The Bland–Altman analysis revealed a mean bias of + 4.98 PCI units, indicating a tendency of radiologic imaging to underestimate the extent of disease compared with intraoperative findings, with 95% limits of agreement (LoA) ranging from + 3.39 to + 6.57. A strong positive correlation was observed between rPCI and crsPCI, with a Pearson correlation coefficient (r = 0.74, p < 0.001) and a Spearman’s rho = 0.70 (p < 0.001). The 95% confidence interval (0.60–0.84) supports the robustness of this association. The scatter plot demonstrates this relationship, showing a clear trend where higher rPCI values correspond to higher intraoperative PCI scores. (Figs. 3 and 4 ) Laparoscopic PCI Assessment Laparoscopic PCI data were available for 16 patients. The mean lpPCI was 7.81 (IQR 3–7.25), closely matching the crsPCI in this subset. The agreement between lpPCI and crsPCI was excellent, with an ICC = 0.94 (95% CI 0.85–0.98). The Bland–Altman plot showed a mean bias of − 1.5 units (95% LoA − 7.04 to + 4.04), suggesting that laparoscopy provided a slightly lower but highly consistent estimate of tumor burden. Correlation analyses confirmed these findings, with Pearson’s r = 0.94 (p < 0.00001) and Spearman’s rho = 0.75 (p = 0.0009), demonstrating strong agreement between the laparoscopic and surgical PCI measurements. (Figs. 3 and 4 ) Subgroup Analysis When stratified by primary tumor type, the radiologic PCI tended to underestimate disease burden across all groups, particularly in patients with gastric and colorectal cancer, where usually small bowel and mesenteric involvement were more frequently missed. In contrast, laparoscopic assessment provided improved accuracy in gastric cancer cases, correlating closely with intraoperative findings. Table 2 Clinical and Perioperative Characteristics Parameter Radiologic PCI (n = 56) Laparoscopic PCI (n = 16) Cytoreductive surgery PCI (n = 56) Mean 9.25 7.81 14.23 IQR (3–13) (3-7.25) (9-18.5) Age (mean) 57 54 57 BMI (mean) 23.6 21.6 23.6 Gender M (16.07%) F (83.92%) M (37.5%) F(62.5%) M (16.07%) F (83.92%) Primary tumor Ovary 31(55.3%) 3 (18.75%) 31(55.3%) Gastric 13 (23.21%) 12 (75%) 13 (23.21%) Pseudomixoma 5 (8.92%) 1 (6.25%) 5 (8.92%) Colon 2 (3.5%) 0 2 (3.5%) Others 5 (8.92%) 0 5 (8.92%) HIPEC Yes 14 (25%) 9 (75%) 14 (25%) No 42 (75%) 3 (25%) 42 (75%) Cytoreduction CC0 53 (94%) 16 (100%) 53 (94%) CC1 1 (1.78%) 0 1 (1.78%) CC2 2 (3.57%) 0 2 (3.57%) Table 3 Correlation findings Parameter Radiologic PCI (rPCI) Laparoscopic PCI (lapPCI) Surgical PCI (crsPCI) n 56 16 56 Mean PCI (IQR) 9.25 (3–13) 7.81 (3–7.25) 14.23 (9–18.5) ICC (95% CI) 0.82 (0.74–0.88) 0.94 (0.85–0.98) — Mean Bias (LoA) + 4.98 (3.39–6.57) −1.5 (− 7.04–4.04) — Pearson’s r 0.74 (p < 0.001) 0.94 (p < 0.00001) — Spearman’s rho 0.70 (p < 0.001) 0.75 (p = 0.0009) — Discussion This study analyzed the concordance between radiologic (rPCI), laparoscopic (lapPCI), and surgical (crsPCI) peritoneal cancer index assessments in patients undergoing cytoreductive surgery for peritoneal metastases (PM). Our findings demonstrate a strong correlation between radiologic and intraoperative PCI values (ICC = 0.82, r = 0.74), though with a systematic underestimation of disease burden on imaging, while laparoscopic evaluation exhibited excellent agreement with surgical findings (ICC = 0.94, r = 0.94) and minimal bias. These results reinforce the complementary roles of radiologic and laparoscopic staging in the preoperative evaluation of PM, especially in patients with low peritoneal tumor burden. Radiologic Assessment In our series, radiologic PCI showed a good correlation with the intraoperative PCI but tended to underestimate tumor extension by approximately five units on average. This aligns with prior studies showing that conventional CT frequently misses small peritoneal deposits and underestimates PCI, particularly in the small bowel and mesenteric regions 11 , 12 . MRI, used in 70% of our patients, provided slightly better correlation, consistent with evidence indicating that diffusion-weighted MRI improves the detection of small or serosal implants compared to CT 13,14 . Nevertheless, imaging remains limited by the tumor deposit size thresholds (often > 5 mm) and by variations in interpretation, even among experienced radiologists 15 . Emerging modalities such as dual-energy CT, PET/MRI, and fibroblast activation protein inhibitor (FAPI)–PET show promise for improving sensitivity in peritoneal metastases, achieving up to 90% regional sensitivity in a meta-analysis 16 . However, their availability and costs remain limitations for routine use. Our findings reaffirm that imaging should be viewed as a reliable screening and planning tool but not as a definitive staging modality alone. Laparoscopic Evaluation Laparoscopy provided a closer approximation to the intraoperative PCI, with minimal bias (− 1.5 units) and excellent correlation metrics. This superior agreement reflects its direct visualization capacity, which allows for more accurate assessment of peritoneal surfaces and diaphragmatic or subhepatic areas. Previous reports have confirmed laparoscopy’s high accuracy in excluding unresectable disease and its value in preventing non-therapeutic laparotomies 7 , 9 . In our study, laparoscopy was performed primarily in gastric cancer cases, consistent with current guidelines recommending this approach in tumors with high peritoneal dissemination risk. Despite these advantages, diagnostic laparoscopy has recognized limitations. Adhesions, prior surgeries, or inaccessible mesenteric regions can hinder complete evaluation, leading to underestimation of disease extent in up to 60% of cases 8 . Furthermore, the technique is operator-dependent, and reproducibility across centers can vary. Nevertheless, when performed by trained surgical oncologists within specialized units in oncology, laparoscopic PCI remains an invaluable decision-making tool. Clinical Implications Accurate estimation of PCI before CRS is essential, as the PCI strongly correlates with the feasibility of complete cytoreduction 3 , 10 . Our findings suggest that radiologic PCI can assist in stratification by disease extent and help determine surgical candidacy, but laparoscopy adds critical refinement, especially in borderline or high-PCI cases where imaging alone might underestimate disease or alter the decision-making process. In our cohort, this approach likely contributed to the high rate of complete cytoreduction (94%) and low incidence of non-therapeutic laparotomy. In our practical scenario, these results support a multimodal staging algorithm: (1) cross-sectional imaging for initial evaluation and surgical planning, followed by (2) diagnostic laparoscopy in equivocal or high-risk cases, particularly gastric and colorectal tumors, and (3) intraoperative confirmation via surgical PCI as the gold standard. Such integration optimizes patient selection and reduces unnecessary laparotomies, aligning with international consensus recommendations from PSOGI and ESGAR 6 . The magnitude of correlation observed in our series (r = 0.74 for radiology, r = 0.94 for laparoscopy) is comparable to recent studies in ovarian and colorectal PM, which report r-values between 0.70 and 0.90 for rPCI–crsPCI agreement 5 , 10 . The mean bias of + 4.98 units in our rPCI is within the range reported by Goswami et al. (+ 4.2 units) and Ahmed et al. (+ 5–6 units). Similarly, our Bland–Altman limits of agreement are similar with those described in gastric and pseudomyxoma cohorts 9 . These parallels reinforce the reproducibility of our findings across different tumor types and imaging modalities. Strengths and Limitations The main strengths of this study include the use of a prospectively maintained database, standardized PCI scoring across all modalities, and blinded radiologic reassessment. However, limitations should be acknowledged. The retrospective design and limited number of laparoscopic cases may restrict generalizability. The predominance of ovarian and gastric primaries may also introduce tumor-type bias. Patients excluded from CRS based on radiologic or laparoscopic findings were not captured, limiting assessment of true selection performance. Furthermore, interobserver variability in imaging interpretation and surgical scoring could not be fully controlled. Future multicenter, prospective studies with standardized imaging protocols and central review could validate these findings more broadly. Future Directions Advances in quantitative imaging such as radiomics and artificial intelligence (AI)-assisted segmentation may further enhance preoperative PCI estimation and prediction of surgical outcomes. Integration of these technologies with molecular biomarkers and patient-reported outcomes could enable more personalized treatment strategies for peritoneal metastases. Conclusion Radiologic assessment of the PCI demonstrates good concordance with intraoperative (CRS) findings but consistently underestimates the true extent of disease, particularly in regions with small bowel or mesenteric involvement. In contrast, laparoscopic evaluation achieves excellent agreement with the surgical PCI and provides valuable complementary information for patient selection. These results highlight the importance of a multimodal staging approach, integrating radiologic and laparoscopic assessments to enhance accuracy in preoperative decision-making. Such strategies are especially relevant for borderline PCI and questionable resectable cases, including patients with gastric and colorectal cancer. Further prospective, multicenter studies are warranted to validate these findings across different tumor types and to define standardized protocols for PCI assessment. Declarations Author Contributions Silvia Guerrero-Macías conceived and designed the study, coordinated the research process, and led the drafting of the manuscript. Vaneza Ávila-Rodríguez performed the data analysis and contributed to manuscript drafting. Jorge Andrés Urrutia contributed to data collection and participated in manuscript drafting and revision. Daniel Upegui , Carlos Bonilla , and Álvaro Arjona Sánchez contributed to manuscript review and editing. All authors read and approved the final manuscript and consented to its publication. Availability of data and materials Anonymized data supporting the findings are available from the corresponding author upon reasonable request. Supplementary material containing extended results, figures, and tables is provided with the submission. Ethics approval This study was approved by the Institutional Research and Ethics Committee of the CTIC Foundation in Bogotá, Colombia, and was conducted in accordance with the Declaration of Helsinki. Consent to Participate All patients who underwent surgery at our institution provided written informed consent for the use of their clinical data for research purposes. Given the retrospective nature of the present study and the use of anonymized data, no additional informed consent was required. Competing interests The authors declare that they have no competing interests. Funding This work received no specific grant from any funding agency, commercial or not-for-profit sectors. References Wong LCK, Li Z, Fan Q, Tan JW, Tan QX, Wong JSM, et al. Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) in peritoneal sarcomatosis-A systematic review and meta-analysis. Eur J Surg Oncol. 2022;48(3):640–8. 10.1016/j.ejso.2021.10.013 . Foster JM, Sleightholm R, Patel A, Shostrom V, Hall B, Neilsen B, et al. Morbidity and mortality rates following cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy compared with other high-risk surgical oncology procedures. JAMA Netw Open. 2019;2(1):e186847. 10.1001/jamanetworkopen.2018.6847 . Jacquet P, Sugarbaker PH. Clinical research methodologies in diagnosis and staging of patients with peritoneal carcinomatosis. Cancer Treat Res. 1996;82:359–74. 10.1007/978-1-4613-1247-5_23 . Ahmed SA, Abou-Taleb H, Yehia A, El Malek NAA, Siefeldein GS, Badary DM, Jabir MA. 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Ann Surg Oncol. 2025;32(4):2923–31. 10.1245/s10434-024-16737-0 . Epub 2024 Dec 27. PMID: 39730964; PMCID: PMC12244292. Goswami G, et al. Accuracy of CT scan in predicting the surgical PCI in patients undergoing cytoreductive surgery with/without HIPEC: A prospective single-institution study. Indian J Surg Oncol. 2019;10(2):296–302. Garrett C, et al. What is the accuracy, sensitivity and specificity of the radiological peritoneal cancer index in repeat cytoreductive surgery: A retrospective study. World J Surg Oncol. 2025;23(1):138. Chia CS, et al. Prospective comparison of the performance of MRI versus CT in the detection and evaluation of peritoneal surface malignancies. Cancers. 2022;14(13):3179. https://doi.org/10.3390/cancers14133179 . Laghi A, et al. Imaging of peritoneal metastases in ovarian cancer using MDCT, MRI, and FDG PET/CT: A systematic review and meta-analysis. Cancers. 2023;16(8):1467. https://doi.org/10.3390/cancers16081467 . van ’t Sant I, et al. Diagnostic performance of imaging for the detection of peritoneal metastases: A meta-analysis. Eur Radiol. 2020;30(6):3101–12. Passot G, May, on behalf of the BIG-RENAPE Surgery Working Group., Multicentre study of laparoscopic or open assessment of the peritoneal cancer index (BIG-RENAPE), BJS , Volume 105, Issue 6, 2018, Pages 663–667. https://doi.org/10.1002/bjs.10723 Additional Declarations No competing interests reported. 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Ávila-Rodríguez","email":"","orcid":"","institution":"Centro de Investigación y Tratamiento para el cáncer (CTIC)","correspondingAuthor":false,"prefix":"","firstName":"Vaneza","middleName":"","lastName":"Ávila-Rodríguez","suffix":""},{"id":594835155,"identity":"f5d2561f-3c1a-4c44-a159-5337a843613b","order_by":2,"name":"Jorge Andrés Urrutia","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5ElEQVRIiWNgGAWjYBACxgYwJcHAwA5iFQDxAaK0JAC18ICUGhChBQISQBYlEKmFeUbus8+8Pyzk5SPfmD34YcAgx3cjgfHDB3wOm5FuPJsnQcJw4+0cc8MeAwZjyRsJzJIz8GpJY2YGamHcODvHTILHgCFxw40ENmYeIrTYb5x5xkzyjwFDPdFaEudL8JhJA21JMCCopecZM+OcNInkDTxpZdIyBhKGM888bMbrF8P2NGaGNzZ1tvPbD2+TfFNhI893PPkg3hAzbIAyDA6AKQkGeIrABeThDPzqRsEoGAWjYCQDAL4YQ+G3fc5gAAAAAElFTkSuQmCC","orcid":"","institution":"Instituto Nacional de Cancerología","correspondingAuthor":true,"prefix":"","firstName":"Jorge","middleName":"Andrés","lastName":"Urrutia","suffix":""},{"id":594835157,"identity":"71f6443e-8f6a-4959-a64b-100605d166ca","order_by":3,"name":"Daniel Upegui","email":"","orcid":"","institution":"Centro de Investigación y Tratamiento para el cáncer (CTIC)","correspondingAuthor":false,"prefix":"","firstName":"Daniel","middleName":"","lastName":"Upegui","suffix":""},{"id":594835159,"identity":"9b5b4da0-eb0e-4c82-9480-54c8ad7a8473","order_by":4,"name":"Carlos Bonilla","email":"","orcid":"","institution":"Centro de Investigación y Tratamiento para el cáncer (CTIC)","correspondingAuthor":false,"prefix":"","firstName":"Carlos","middleName":"","lastName":"Bonilla","suffix":""},{"id":594835175,"identity":"d27950fc-25d6-4c7d-a91d-52a7352a2ab8","order_by":5,"name":"Alvaro Arjona Sánchez","email":"","orcid":"","institution":"Hospital Reina Sofía","correspondingAuthor":false,"prefix":"","firstName":"Alvaro","middleName":"Arjona","lastName":"Sánchez","suffix":""}],"badges":[],"createdAt":"2026-01-31 06:09:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8746936/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8746936/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103345382,"identity":"bc91b3a2-5efe-4d20-8d79-05a051795c01","added_by":"auto","created_at":"2026-02-24 16:11:46","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":88941,"visible":true,"origin":"","legend":"\u003cp\u003eFlow chart patient selection and study cohort\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8746936/v1/539ea69227968b5b7f1d612b.png"},{"id":103345381,"identity":"a722e153-3971-4e34-a2a4-43fc65830367","added_by":"auto","created_at":"2026-02-24 16:11:46","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":165438,"visible":true,"origin":"","legend":"\u003cp\u003eRadiological evaluation of PCI in CT and MRI\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8746936/v1/45385dea6d105258cd9a52f4.png"},{"id":103345380,"identity":"dd7ba4ef-5ea6-4bdc-a662-c24b55a21605","added_by":"auto","created_at":"2026-02-24 16:11:46","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":266931,"visible":true,"origin":"","legend":"\u003cp\u003eBland–Altman plot for crsPCI vs. rPCI (left) and crsPCI vs. lapPCI (right)\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8746936/v1/0c746c5bdf0983fe9de70fe4.jpeg"},{"id":103506572,"identity":"2097c8f8-27d2-422e-a7b3-e81fc1fd2539","added_by":"auto","created_at":"2026-02-26 13:37:43","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":130198,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plot illustrating the correlation between intraoperative surgical peritoneal cancer index (crsPCI) and preoperative imaging peritoneal cancer index (rPCI).\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8746936/v1/ef5971524c9eb7966419c5a4.jpeg"},{"id":103509564,"identity":"6818bb84-9b4b-43f7-8fc6-6aaf62347cde","added_by":"auto","created_at":"2026-02-26 13:59:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1612179,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8746936/v1/c80ba0b8-2980-414c-bc8a-995542c9ec13.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Concordance among radiological, laparoscopic and laparotomic peritoneal cancer index assessments in patients undergoing cytoreductive surgery for peritoneal metastases","fulltext":[{"header":"Background","content":"\u003cp\u003ePeritoneal metastases (PM) represent a complex and heterogeneous manifestation of advanced abdominal and gynecologic malignancies. In selected patients, the combined use of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) has changed the natural history of PM, offering prolonged survival and, in some cases, long-term disease control. Accurate preoperative staging and quantification of peritoneal disease are therefore essential to select patients who are likely to benefit from this surgical approach while avoiding non-therapeutic laparotomies and unnecessary morbidity\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eJacquet and Sugarbaker introduced a standardized, reproducible system for estimating the extent and distribution of peritoneal carcinomatosis: the Peritoneal Cancer Index (PCI). The PCI divides the abdominal cavity into 13 regions and assigns a lesion-size score in each region, producing a value (0\u0026ndash;39) that reflects overall tumor burden. The surgical PCI remains one of the most important prognostic indicators for patients considered for CRS, correlating strongly with the probability of achieving complete cytoreduction and with overall survival\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePreoperative estimation of PCI is commonly attempted with cross-sectional imaging such as contrast-enhanced computed tomography (CT). However, conventional imaging frequently underestimates tumor burden, particularly in the small bowel and mesenteric regions, with multiple series and meta-analyses reporting systematic underestimation of surgical PCI by CT and variable sensitivity across regions and lesion sizes\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Advanced imaging approaches (MRI with diffusion-weighted imaging, dual-energy CT, and hybrid PET/MRI or novel tracers such as FAPI) are improving detection but limitations persist, especially for small-volume and serosal disease\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eDiagnostic laparoscopy offers direct visualization of peritoneal surfaces and has been proposed as an intermediate staging tool to complement imaging. Multiple cohorts and prospective series show that diagnostic laparoscopy improves patient selection for CRS-HIPEC and reduces the rate of non-therapeutic laparotomies by detecting unresectable disease that was missed on imaging\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. However, laparoscopic PCI has some limitations: peritoneal adhesions, hidden spaces or restricted visualization of some small-bowel surfaces may produce discordance with the subsequent open (laparotomic) assessment. Interobserver variability and the experience of the operator also affect laparoscopic scoring reproducibility\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eTreatment decisions in peritoneal malignancies, particularly the indication of CRS and planned resection extension, depend heavily on accurate preoperative Peritoneal Cancer Index (PCI) estimation. Consequently, determining the level of agreement among radiological, laparoscopic, and laparotomic PCI assessments is fundamental for an optimal patient selection. A better understanding of the concordance of staging models could help in the selection and work-up for these patients adding the laparoscopy or not after imaging tests.\u003c/p\u003e \u003cp\u003eAccordingly, this study aims to quantify the agreement between preoperative radiological (rPCI) and laparoscopic (lapPCI) assessments versus the intraoperative laparotomic PCI (crsPCI) in patients underwent CRS for peritoneal metastases, and to explore the potential implications of PCI discordance for preoperative staging and surgical planning in patients undergoing CRS.\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\u003eSensitivity of Different Modalities in Detecting Peritoneal Disease (overall and by region)\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\u003eModality / Clinical Scenario\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall Sensitivity / Accuracy\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRegion-Specific Performance\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCT vs Surgical PCI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall concordance with surgical PCI\u0026thinsp;~\u0026thinsp;30%. CT underestimated PCI in ~\u0026thinsp;46% and overestimated in ~\u0026thinsp;24% of cases\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAccuracy varied by region (\u0026asymp;\u0026thinsp;60\u0026ndash;80%). Upper abdominal regions (PCI 1\u0026ndash;3): ~60\u0026ndash;70%. Small bowel regions (PCI 9\u0026ndash;12): ~60\u0026ndash;80%, with frequent underestimation of disease extent\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRadiologic PCI (CT and FDG-PET) in Repeat CRS/HIPEC\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall sensitivity\u0026thinsp;~\u0026thinsp;30.8%; specificity\u0026thinsp;~\u0026thinsp;79.9% for radiologic PCI\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHigh sensitivity in pelvic regions (~\u0026thinsp;80\u0026ndash;87.5%). Very low sensitivity in epigastric regions (0\u0026ndash;25%) and small bowel regions (25\u0026ndash;33%) for both CT and FDG-PET\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMRI vs CT for Detection of Peritoneal Surface Malignancies\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMRI: ~49.1%; CT: ~47.8% (averaged across all PCI regions).\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSmall bowel regions (PCI 9\u0026ndash;12): MRI\u0026thinsp;~\u0026thinsp;19\u0026ndash;31%, CT\u0026thinsp;~\u0026thinsp;0\u0026ndash;7%. Moderate to good sensitivity (~\u0026thinsp;58\u0026ndash;79%) in several upper, lower, and flank regions (PCI 1, 3\u0026ndash;8).\u003csup\u003e13\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMeta-analysis of Imaging Modalities (CT, PET/CT, DW-MRI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCT: ~68%; PET/CT: ~80%; DW-MRI: ~92% (overall sensitivity for peritoneal metastasis detection).\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRegion-based analysis shows reduced sensitivity of CT in small bowel regions. CT region-based specificity\u0026thinsp;~\u0026thinsp;88%. PET/CT and DW-MRI demonstrated superior performance across most regions.\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLaparoscopy vs Open Exploration (PCI Assessment)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExact PCI concordance\u0026thinsp;~\u0026thinsp;25.6%; underestimation in ~\u0026thinsp;62.8%; overestimation in ~\u0026thinsp;11.6% of cases.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMisestimation more frequent in regions involving small bowel. Accuracy was not influenced by tumor type or prior systemic therapy.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCT Accuracy in Predicting Resectability / CRS Feasibility\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCT sensitivity for predicting complete cytoreduction\u0026thinsp;~\u0026thinsp;35\u0026ndash;45%, with limited ability to exclude unresectable disease.\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLowest accuracy observed in small bowel and mesenteric regions; better performance in pelvis and paracolic gutters.\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\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"},{"header":"Methods","content":"\u003cp\u003eWe conducted a retrospective cohort study including all patients who underwent CRS for peritoneal metastases at Centro de Investigaci\u0026oacute;n y Tratamiento del C\u0026aacute;ncer Luis Carlos Sarmiento Angulo (CTIC) Foundation, between August 2023 and February 2025. Patients were identified from a prospectively maintained institutional database. Cases were eligible if complete data were available for preoperative imaging, diagnostic laparoscopy, and crsPCI assessment. Patients with incomplete documentation, palliative intent procedures, or non-oncologic peritoneal disease were excluded. This analysis includes only patients who proceeded to CRS; patients deemed unresectable preoperatively were not captured (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eRadiologic Evaluation\u003c/h2\u003e \u003cp\u003eAll patients underwent CT or MRI of the chest, abdomen, and pelvis as part of the preoperative workup was done. A radiologist with expertise in peritoneal surface malignancies, blinded to surgical and laparoscopic findings, retrospectively reviewed the imaging studies to assign a radiological peritoneal cancer index (rPCI) following the 13-regions distribution and lesion size criteria described by Jacquet and Sugarbaker. Each lesion was scored from 0 to 3 according to the largest nodule size in each region, and the sum provided the total rPCI (0\u0026ndash;39). (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eLaparoscopic Evaluation\u003c/h3\u003e\n\u003cp\u003eWhen diagnostic laparoscopy was performed prior to CRS, operative reports and intraoperative images were reviewed to extract the lapPCI. All laparoscopic procedures were performed by surgeons trained in peritoneal surface malignancies, using a systematic inspection of the 13 abdominopelvic regions. Adhesions or limited visualization were documented. The lapPCI value used for analysis corresponded to the surgeon\u0026rsquo;s recorded total score at the time of laparoscopy.\u003c/p\u003e\n\u003ch3\u003eOpen (cytoreductive surgery) assessment\u003c/h3\u003e\n\u003cp\u003eThe crsPCI, obtained during open cytoreductive surgery, was considered the reference standard. The scoring was performed systematically after complete exploration of all peritoneal regions, before starting cytoreduction. When available, photographic or video documentation was used to confirm regional lesion assignment and improve inter-observer variability.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eDescriptive statistics were used to summarize demographic and clinical variables. Agreement between rPCI, lapPCI, and crsPCI was analyzed using the Bland\u0026ndash;Altman method to estimate bias (mean difference) and 95% limits of agreement. The intraclass correlation coefficient (ICC) was calculated to assess overall concordance, with values interpreted as: poor (\u0026lt;\u0026thinsp;0.5), moderate (0.5\u0026ndash;0.75), good (0.75\u0026ndash;0.9), and excellent (\u0026gt;\u0026thinsp;0.9). Pearson\u0026rsquo;s correlation coefficient was used for linear association of continuous PCI values, while Spearman\u0026rsquo;s rank correlation assessed ordinal relationships and non-parametric distributions.\u003c/p\u003e \u003cp\u003eAdditionally, subgroup analyses were conducted according to:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003ePrimary tumor origin (colorectal, appendiceal, gastric, ovarian, others),\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ePCI categories (low\u0026thinsp;\u0026le;\u0026thinsp;10, intermediate 11\u0026ndash;20, high\u0026thinsp;\u0026gt;\u0026thinsp;20).\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eDifferences between modalities were compared using paired-sample t tests or Wilcoxon signed-rank tests as appropriate. Statistical analyses were performed using SPSS version 29.0 (IBM Corp., Armonk, NY, USA) and R version 4.3.1 (R Foundation for Statistical Computing, Vienna, Austria). A two-tailed \u003cem\u003ep\u003c/em\u003e value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEthical Considerations\u003c/h3\u003e\n\u003cp\u003e The study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the Institutional Review Board.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 56 patients who underwent cytoreductive surgery for peritoneal metastases between August 2023 and February 2025 were included in the analysis. All patients had preoperative radiologic assessment (rPCI), performed using magnetic resonance imaging (MRI) in 70% and computed tomography (CT) in 30% of cases. Laparoscopic PCI (lapPCI) was available for 16 patients (28.5%), most frequently among those with gastric cancer (80%). The median age was 57 years (IQR 48\u0026ndash;64), and the majority were female (83.9%). Ovarian cancer represented the predominant primary tumor (55.3%), followed by gastric (23.2%), pseudomyxoma peritonei (8.9%), colorectal (3.5%), and others (8.9%). Mean body mass index (BMI) was 23.6 kg/m\u0026sup2;. Complete cytoreduction (CC-0) was achieved in 94% of cases, and HIPEC was performed in 25% (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eRadiologic PCI Assessment\u003c/h3\u003e\n\u003cp\u003eThe mean rPCI was 9.25 (IQR 3\u0026ndash;13), compared with a mean surgical PCI (crsPCI) of 14.23 (IQR 9\u0026ndash;18.5). Radiologic evaluation showed a good level of agreement with the surgical PCI, with an intraclass correlation coefficient (ICC) of 0.82 (95% CI 0.74\u0026ndash;0.88). The Bland\u0026ndash;Altman analysis revealed a mean bias of +\u0026thinsp;4.98 PCI units, indicating a tendency of radiologic imaging to underestimate the extent of disease compared with intraoperative findings, with 95% limits of agreement (LoA) ranging from +\u0026thinsp;3.39 to +\u0026thinsp;6.57.\u003c/p\u003e \u003cp\u003eA strong positive correlation was observed between rPCI and crsPCI, with a Pearson correlation coefficient (r\u0026thinsp;=\u0026thinsp;0.74, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and a Spearman\u0026rsquo;s rho\u0026thinsp;=\u0026thinsp;0.70 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The 95% confidence interval (0.60\u0026ndash;0.84) supports the robustness of this association. The scatter plot demonstrates this relationship, showing a clear trend where higher rPCI values correspond to higher intraoperative PCI scores. (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e\n\u003ch3\u003eLaparoscopic PCI Assessment\u003c/h3\u003e\n\u003cp\u003eLaparoscopic PCI data were available for 16 patients. The mean lpPCI was 7.81 (IQR 3\u0026ndash;7.25), closely matching the crsPCI in this subset. The agreement between lpPCI and crsPCI was excellent, with an ICC\u0026thinsp;=\u0026thinsp;0.94 (95% CI 0.85\u0026ndash;0.98). The Bland\u0026ndash;Altman plot showed a mean bias of \u0026minus;\u0026thinsp;1.5 units (95% LoA \u0026minus;\u0026thinsp;7.04 to +\u0026thinsp;4.04), suggesting that laparoscopy provided a slightly lower but highly consistent estimate of tumor burden.\u003c/p\u003e \u003cp\u003eCorrelation analyses confirmed these findings, with Pearson\u0026rsquo;s r\u0026thinsp;=\u0026thinsp;0.94 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.00001) and Spearman\u0026rsquo;s rho\u0026thinsp;=\u0026thinsp;0.75 (p\u0026thinsp;=\u0026thinsp;0.0009), demonstrating strong agreement between the laparoscopic and surgical PCI measurements. (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eSubgroup Analysis\u003c/h2\u003e \u003cp\u003eWhen stratified by primary tumor type, the radiologic PCI tended to underestimate disease burden across all groups, particularly in patients with gastric and colorectal cancer, where usually small bowel and mesenteric involvement were more frequently missed. In contrast, laparoscopic assessment provided improved accuracy in gastric cancer cases, correlating closely with intraoperative findings.\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\u003eClinical and Perioperative Characteristics\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=\"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=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRadiologic PCI\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;56)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLaparoscopic PCI\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;16)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCytoreductive surgery PCI (n\u0026thinsp;=\u0026thinsp;56)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIQR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(3\u0026ndash;13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(3-7.25)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(9-18.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (mean)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (mean)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM (16.07%) F (83.92%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM (37.5%) F(62.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eM (16.07%) F (83.92%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrimary tumor\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOvary\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31(55.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (18.75%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31(55.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGastric\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (23.21%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (75%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13 (23.21%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePseudomixoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (8.92%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (6.25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (8.92%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eColon\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (3.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (3.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOthers\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (8.92%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (8.92%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHIPEC\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (75%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14 (25%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42 (75%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42 (75%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCytoreduction\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCC0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53 (94%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e53 (94%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCC1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1.78%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (1.78%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCC2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (3.57%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (3.57%)\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\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\u003eCorrelation findings\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=\"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=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRadiologic PCI (rPCI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLaparoscopic PCI (lapPCI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSurgical PCI (crsPCI)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean PCI (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.25 (3\u0026ndash;13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.81 (3\u0026ndash;7.25)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14.23 (9\u0026ndash;18.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eICC (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.82 (0.74\u0026ndash;0.88)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.94 (0.85\u0026ndash;0.98)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Bias (LoA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e+\u0026thinsp;4.98 (3.39\u0026ndash;6.57)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;1.5 (\u0026minus;\u0026thinsp;7.04\u0026ndash;4.04)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePearson\u0026rsquo;s r\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.74 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.94 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.00001)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpearman\u0026rsquo;s rho\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.70 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.75 (p\u0026thinsp;=\u0026thinsp;0.0009)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026mdash;\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\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study analyzed the concordance between radiologic (rPCI), laparoscopic (lapPCI), and surgical (crsPCI) peritoneal cancer index assessments in patients undergoing cytoreductive surgery for peritoneal metastases (PM). Our findings demonstrate a strong correlation between radiologic and intraoperative PCI values (ICC\u0026thinsp;=\u0026thinsp;0.82, r\u0026thinsp;=\u0026thinsp;0.74), though with a systematic underestimation of disease burden on imaging, while laparoscopic evaluation exhibited excellent agreement with surgical findings (ICC\u0026thinsp;=\u0026thinsp;0.94, r\u0026thinsp;=\u0026thinsp;0.94) and minimal bias. These results reinforce the complementary roles of radiologic and laparoscopic staging in the preoperative evaluation of PM, especially in patients with low peritoneal tumor burden.\u003c/p\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eRadiologic Assessment\u003c/h2\u003e \u003cp\u003eIn our series, radiologic PCI showed a good correlation with the intraoperative PCI but tended to underestimate tumor extension by approximately five units on average. This aligns with prior studies showing that conventional CT frequently misses small peritoneal deposits and underestimates PCI, particularly in the small bowel and mesenteric regions\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. MRI, used in 70% of our patients, provided slightly better correlation, consistent with evidence indicating that diffusion-weighted MRI improves the detection of small or serosal implants compared to CT\u003csup\u003e13,14\u003c/sup\u003e. Nevertheless, imaging remains limited by the tumor deposit size thresholds (often\u0026thinsp;\u0026gt;\u0026thinsp;5 mm) and by variations in interpretation, even among experienced radiologists\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eEmerging modalities such as dual-energy CT, PET/MRI, and fibroblast activation protein inhibitor (FAPI)\u0026ndash;PET show promise for improving sensitivity in peritoneal metastases, achieving up to 90% regional sensitivity in a meta-analysis\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. However, their availability and costs remain limitations for routine use. Our findings reaffirm that imaging should be viewed as a reliable screening and planning tool but not as a definitive staging modality alone.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eLaparoscopic Evaluation\u003c/h2\u003e \u003cp\u003eLaparoscopy provided a closer approximation to the intraoperative PCI, with minimal bias (\u0026minus;\u0026thinsp;1.5 units) and excellent correlation metrics. This superior agreement reflects its direct visualization capacity, which allows for more accurate assessment of peritoneal surfaces and diaphragmatic or subhepatic areas. Previous reports have confirmed laparoscopy\u0026rsquo;s high accuracy in excluding unresectable disease and its value in preventing non-therapeutic laparotomies\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. In our study, laparoscopy was performed primarily in gastric cancer cases, consistent with current guidelines recommending this approach in tumors with high peritoneal dissemination risk.\u003c/p\u003e \u003cp\u003eDespite these advantages, diagnostic laparoscopy has recognized limitations. Adhesions, prior surgeries, or inaccessible mesenteric regions can hinder complete evaluation, leading to underestimation of disease extent in up to 60% of cases\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Furthermore, the technique is operator-dependent, and reproducibility across centers can vary. Nevertheless, when performed by trained surgical oncologists within specialized units in oncology, laparoscopic PCI remains an invaluable decision-making tool.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eClinical Implications\u003c/h2\u003e \u003cp\u003eAccurate estimation of PCI before CRS is essential, as the PCI strongly correlates with the feasibility of complete cytoreduction\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Our findings suggest that radiologic PCI can assist in stratification by disease extent and help determine surgical candidacy, but laparoscopy adds critical refinement, especially in borderline or high-PCI cases where imaging alone might underestimate disease or alter the decision-making process. In our cohort, this approach likely contributed to the high rate of complete cytoreduction (94%) and low incidence of non-therapeutic laparotomy.\u003c/p\u003e \u003cp\u003eIn our practical scenario, these results support a multimodal staging algorithm: (1) cross-sectional imaging for initial evaluation and surgical planning, followed by (2) diagnostic laparoscopy in equivocal or high-risk cases, particularly gastric and colorectal tumors, and (3) intraoperative confirmation via surgical PCI as the gold standard. Such integration optimizes patient selection and reduces unnecessary laparotomies, aligning with international consensus recommendations from PSOGI and ESGAR\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe magnitude of correlation observed in our series (r\u0026thinsp;=\u0026thinsp;0.74 for radiology, r\u0026thinsp;=\u0026thinsp;0.94 for laparoscopy) is comparable to recent studies in ovarian and colorectal PM, which report r-values between 0.70 and 0.90 for rPCI\u0026ndash;crsPCI agreement\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. The mean bias of +\u0026thinsp;4.98 units in our rPCI is within the range reported by Goswami et al. (+\u0026thinsp;4.2 units) and Ahmed et al. (+\u0026thinsp;5\u0026ndash;6 units). Similarly, our Bland\u0026ndash;Altman limits of agreement are similar with those described in gastric and pseudomyxoma cohorts\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. These parallels reinforce the reproducibility of our findings across different tumor types and imaging modalities.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eStrengths and Limitations\u003c/h2\u003e \u003cp\u003eThe main strengths of this study include the use of a prospectively maintained database, standardized PCI scoring across all modalities, and blinded radiologic reassessment. However, limitations should be acknowledged. The retrospective design and limited number of laparoscopic cases may restrict generalizability. The predominance of ovarian and gastric primaries may also introduce tumor-type bias. Patients excluded from CRS based on radiologic or laparoscopic findings were not captured, limiting assessment of true selection performance. Furthermore, interobserver variability in imaging interpretation and surgical scoring could not be fully controlled. Future multicenter, prospective studies with standardized imaging protocols and central review could validate these findings more broadly.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eFuture Directions\u003c/h2\u003e \u003cp\u003eAdvances in quantitative imaging such as radiomics and artificial intelligence (AI)-assisted segmentation may further enhance preoperative PCI estimation and prediction of surgical outcomes. Integration of these technologies with molecular biomarkers and patient-reported outcomes could enable more personalized treatment strategies for peritoneal metastases.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eRadiologic assessment of the PCI demonstrates good concordance with intraoperative (CRS) findings but consistently underestimates the true extent of disease, particularly in regions with small bowel or mesenteric involvement. In contrast, laparoscopic evaluation achieves excellent agreement with the surgical PCI and provides valuable complementary information for patient selection. These results highlight the importance of a multimodal staging approach, integrating radiologic and laparoscopic assessments to enhance accuracy in preoperative decision-making. Such strategies are especially relevant for borderline PCI and questionable resectable cases, including patients with gastric and colorectal cancer. Further prospective, multicenter studies are warranted to validate these findings across different tumor types and to define standardized protocols for PCI assessment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSilvia Guerrero-Mac\u0026iacute;as\u003c/strong\u003e conceived and designed the study, coordinated the research process, and led the drafting of the manuscript. \u003cstrong\u003eVaneza \u0026Aacute;vila-Rodr\u0026iacute;guez\u003c/strong\u003e performed the data analysis and contributed to manuscript drafting. \u003cstrong\u003eJorge Andr\u0026eacute;s Urrutia\u003c/strong\u003e contributed to data collection and participated in manuscript drafting and revision. \u003cstrong\u003eDaniel Upegui\u003c/strong\u003e, \u003cstrong\u003eCarlos Bonilla\u003c/strong\u003e, and \u003cstrong\u003e\u0026Aacute;lvaro Arjona S\u0026aacute;nchez\u003c/strong\u003e contributed to manuscript review and editing. All authors read and approved the final manuscript and consented to its publication.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnonymized data supporting the findings are available from the corresponding author upon reasonable request. Supplementary material containing extended results, figures, and tables is provided with the submission.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Research and Ethics Committee of the CTIC Foundation in Bogot\u0026aacute;, Colombia, and was conducted in accordance with the Declaration of Helsinki.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll patients who underwent surgery at our institution provided written informed consent for the use of their clinical data for research purposes. Given the retrospective nature of the present study and the use of anonymized data, no additional informed consent was required.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work received no specific grant from any funding agency, commercial or not-for-profit sectors.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWong LCK, Li Z, Fan Q, Tan JW, Tan QX, Wong JSM, et al. Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) in peritoneal sarcomatosis-A systematic review and meta-analysis. 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Eur Radiol. 2020;30(6):3101\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePassot G, May, on behalf of the BIG-RENAPE Surgery Working Group., Multicentre study of laparoscopic or open assessment of the peritoneal cancer index (BIG-RENAPE), \u003cem\u003eBJS\u003c/em\u003e, Volume 105, Issue 6, 2018, Pages 663\u0026ndash;667. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/bjs.10723\u003c/span\u003e\u003cspan address=\"10.1002/bjs.10723\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-gastrointestinal-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ijgc","sideBox":"Learn more about [Journal of Gastrointestinal Cancer](https://www.springer.com/journal/12029)","snPcode":"12029","submissionUrl":"https://submission.nature.com/new-submission/12029/3","title":"Journal of Gastrointestinal Cancer","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Peritoneal Neoplasms, Peritoneal Cancer Index, Cytoreductive Surgery, Diagnostic Imaging, Laparoscopy","lastPublishedDoi":"10.21203/rs.3.rs-8746936/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8746936/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eAccurate preoperative estimation of the Peritoneal Cancer Index (PCI) is essential for optimal patient selection and surgical planning in peritoneal metastases. This study aimed to quantify the agreement between preoperative radiological PCI (rPCI) and laparoscopic PCI (lapPCI) compared with intraoperative laparotomic PCI (crsPCI) in patients undergoing cytoreductive surgery (CRS), and to explore the potential implications of PCI discordance for preoperative staging.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe conducted a retrospective cohort study including patients who underwent CRS for peritoneal metastases at a tertiary cancer center between August 2023 and February 2025. All patients had preoperative cross-sectional imaging, and a subset underwent diagnostic laparoscopy. Radiological PCI was retrospectively assigned by an experienced radiologist blinded to surgical findings. Agreement between rPCI, lapPCI, and crsPCI was assessed using intraclass correlation coefficients (ICC), Bland\u0026ndash;Altman analysis, and correlation statistics.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eFifty-six patients were included. Preoperative imaging consisted of MRI in 70% and CT in 30% of cases. Laparoscopic PCI was available in 16 patients (28.5%). The mean rPCI was 9.25 (IQR 3\u0026ndash;13), compared with a mean crsPCI of 14.23 (IQR 9\u0026ndash;18.5). Radiologic assessment showed good agreement with surgical PCI (ICC\u0026thinsp;=\u0026thinsp;0.82; 95% CI 0.74\u0026ndash;0.88), but systematically underestimated disease extent, with a mean bias of +\u0026thinsp;4.98 PCI units. Laparoscopic PCI demonstrated excellent agreement with crsPCI (ICC\u0026thinsp;=\u0026thinsp;0.94; 95% CI 0.85\u0026ndash;0.98) and minimal bias (\u0026minus;\u0026thinsp;1.5 PCI units). Correlation analyses supported these findings.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eRadiologic PCI demonstrates good concordance with intraoperative findings but consistently underestimates tumor burden. In contrast, laparoscopic assessment provides excellent agreement with surgical PCI and offers valuable complementary information for preoperative staging. These results support a multimodal staging approach integrating radiologic and laparoscopic evaluation to improve accuracy in patient selection for CRS.\u003c/p\u003e","manuscriptTitle":"Concordance among radiological, laparoscopic and laparotomic peritoneal cancer index assessments in patients undergoing cytoreductive surgery for peritoneal metastases","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-24 16:11:41","doi":"10.21203/rs.3.rs-8746936/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-17T09:33:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-01T20:09:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"266923317760637264234211374836660854497","date":"2026-04-30T12:40:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"239625023364496281264846113483801637230","date":"2026-04-27T14:29:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"102996429657900141554927776595246832857","date":"2026-02-19T08:00:43+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-19T02:09:08+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-14T01:49:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-11T14:05:37+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Gastrointestinal Cancer","date":"2026-01-31T05:58:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-gastrointestinal-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ijgc","sideBox":"Learn more about [Journal of Gastrointestinal Cancer](https://www.springer.com/journal/12029)","snPcode":"12029","submissionUrl":"https://submission.nature.com/new-submission/12029/3","title":"Journal of Gastrointestinal Cancer","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"1bd7f03d-ffc6-49a2-859f-7ae88967c114","owner":[],"postedDate":"February 24th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-17T09:33:53+00:00","index":74,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-01T20:09:50+00:00","index":73,"fulltext":""},{"type":"reviewerAgreed","content":"266923317760637264234211374836660854497","date":"2026-04-30T12:40:39+00:00","index":72,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-24T16:11:41+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-24 16:11:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8746936","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8746936","identity":"rs-8746936","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}