Postoperative Complications Following Prepectoral Versus Subpectoral Tissue Expander Placement in Immediate Breast Reconstruction: A Retrospective Study from Japan

Postoperative Complications Following Prepectoral Versus Subpectoral Tissue Expander Placement in Immediate Breast Reconstruction: A Retrospective Study from Japan | 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 Postoperative Complications Following Prepectoral Versus Subpectoral Tissue Expander Placement in Immediate Breast Reconstruction: A Retrospective Study from Japan Ryotaro Miyano, Tomohiro Shiraishi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7048730/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Sep, 2025 Read the published version in Breast Cancer → Version 1 posted 4 You are reading this latest preprint version Abstract Background: Prepectoral implant placement has become a widely adopted alternative to subpectoral reconstruction in implant-based breast surgery, offering reduced postoperative pain and improved aesthetic outcomes. However, in Japan, prepectoral placement of silicone breast implants (SBIs) remains unapproved, and its clinical safety has not been well established. Methods: We conducted a retrospective review of 176 patients (187 breasts) who underwent immediate two-stage breast reconstruction with tissue expander (TE) placement between January 2023 and December 2024. Patients were categorized into prepectoral (128 patients, 135 breasts) and subpectoral (48 patients, 52 breasts) groups. Postoperative complications including infection, seroma, and TE exposure were compared. Univariate and multivariate logistic regression analyses were performed to identify risk factors. Results: Infection unrelated to necrosis was more frequent in the prepectoral group (13.3% vs. 2.2%, p = 0.03), with 14 of 17 cases requiring invasive treatment and 10 leading to TE removal or unplanned autologous reconstruction. Seroma occurred in 15.6% of prepectoral cases versus 1.9% of subpectoral (p = 0.01), and TE exposure occurred only in the prepectoral group (4.6%). Multivariate analysis identified prepectoral placement and a final fill ratio <0.6 as independent predictors of infection. Prepectoral placement was also the sole predictor for seroma. Conclusions: Prepectoral TE placement in Japanese patients was associated with increased risks of infection, seroma, and TE exposure compared to subpectoral placement. These findings suggest the need for careful patient selection and surgical planning in the context of Japanese clinical practice, where prepectoral SBI use is not yet established. Introduction Prepectoral implant placement has emerged as a significant advancement in implant-based breast reconstruction, offering an alternative to the traditional subpectoral approach.( 1 – 3 ) This technique avoids the subpectoral plane and preserves the pectoralis major muscle, which has been associated with reduced postoperative pain, faster recovery, and elimination of animation deformity compared to traditional subpectoral reconstruction.( 1 , 2 ) Several studies from Western countries have demonstrated comparable complication rates between prepectoral and subpectoral approaches, while highlighting the aesthetic and functional benefits of prepectoral reconstruction.( 2 , 4 ) In Japan, however, direct-to-implant (DTI) reconstruction using a prepectoral approach remains unapproved, and prepectoral silicone breast implant (SBI) placement is not yet an established practice. According to the 2023 clinical practice guidelines issued by the Japan Oncoplastic Breast Surgery Society, subpectoral placement is recommended for SBI.( 5 ) As a result, there are currently no clinical data regarding prepectoral SBI placement in Japanese patients. Nonetheless, immediate two-stage reconstruction with prepectoral tissue expander (TE) placement is permitted in cases where autologous reconstruction is planned. Evaluating the complications associated with prepectoral TE placement may provide critical preliminary evidence to inform the future adoption of prepectoral SBI placement in Japan. This study aimed to retrospectively compare postoperative complication rates between prepectoral and subpectoral TE placement in a Japanese cohort, focusing on infection, seroma, and TE exposure. We hope our findings will contribute to safer and more informed surgical decision-making in breast reconstruction. Materials and Methods We retrospectively reviewed the medical records of patients who underwent mastectomy followed by immediate two-stage breast reconstruction with TE placement between January 2023 and December 2024. Patients were categorized into two groups according to the TE placement plane: prepectoral or subpectoral. Data were collected from clinical records, including patient characteristics: age, body mass index (BMI), smoking status, comorbidities such as diabetes mellitus (DM), hypertension (HTN), corticosteroid use, and other conditions potentially affecting wound healing; prior breast cancer history and treatments (surgery, chemotherapy, hormone therapy, targeted therapy, radiation); current cancer clinical stage; presence and type of neoadjuvant therapy; surgical procedure (nipple-sparing mastectomy [NSM], skin-sparing mastectomy [SSM], or total mastectomy [TM]); mastectomy specimen weight; type of axillary surgery (none, sentinel lymph node biopsy [SLNB], axillary lymph node dissection [ALND]); breast surgeon; reconstructive surgeon; type and size of TE; initial fill volume; initial fill ratio (% of nominal volume);final fill volume; final fill ratio (% of nominal volume) pathological stage; and adjuvant therapy administered during TE expansion. A total of 18 breast surgeons and 23 plastic surgeons were involved in the surgeries; due to the large number of operators, analysis by individual surgeon was not performed. This study was approved by the Institutional Review Board of St. Marianna Unversity (Approval No. 6904(B97)) TE placement was determined based on reconstruction plans: prepectoral placement was selected in patients scheduled for subsequent autologous reconstruction, whereas subpectoral placement was used in patients planning implant-based reconstruction or undecided between the two options. In patients initially scheduled for prepectoral placement, conversion to subpectoral placement was performed intraoperatively if the mastectomy flap was judged to be too thin. In subpectoral reconstruction, the tissue expander was fully covered whenever possible with the pectoralis major muscle and supplemented by additional soft tissue such as the serratus anterior or its fascia to ensure adequate coverage. Two drains were inserted into the subcutaneous space in the prepectoral group. In the subpectoral group, one drain was placed under the pectoralis major muscle, and an additional axillary drain was inserted when axillary dissection was performed. Drains were removed once output was < 30 mL/day; antibiotics were continued until drain removal. Postoperative complications were reviewed for type, timing, treatment, and clinical course. Infection was considered present if the attending surgeon initiated antibiotic treatment based on clinical signs, characteristics of aspirated fluid, or if wound culture results were positive, as documented in the medical record. Univariate analyses were performed using t-tests for continuous variables and Fisher’s exact test for categorical variables. Multivariate logistic regression was conducted for complications with significant group differences to identify independent predictors. Variables were selected based on p < 0.1 in univariate analysis and the number of events. For continuous variables without established clinical thresholds, cutoff values were determined using receiver operating characteristic (ROC) curve analysis based on the Youden index. The optimal cutoff for age by ROC analysis was 51 years; however, a cutoff of 50 years was used in the final model to improve clinical interpretability and ensure modeling stability. Although older adults are typically defined as ≥ 65 years, only 8 patients (9 breasts) were aged 65 or older, while 88 patients (93 breasts) were aged 50 or older; therefore, 50 years was considered a more practical threshold for stratification. All statistical analyses were performed using EZR version 1.52 (Saitama Medical Center, Jichi Medical University, Saitama, Japan), which is a graphical user interface for R version 4.02 (The R Foundation for Statistical Computing, Vienna, Austria).( 6 ) More precisely, it is a modified version of R commander designed to add statistical functions frequently used in biostatistics. Statistical significance was set at p < 0.05. Results A total of 128 patients (135 breasts) underwent prepectoral TE placement, while 48 patients (52 breasts) received subpectoral placement. Patient characteristics are summarized in Table 1 . Significant differences between the groups were observed in BMI (prepectoral: 23.2 ± 3.8 vs. subpectoral: 21.8 ± 3.7; p = 0.02), history of hypertension (0.74% vs. 7.7%; p = 0.02), use of neoadjuvant targeted therapy (8.1% vs. 0%; p = 0.03), surgical procedure (NSM: 48.9% vs. 71.2%; p = 0.02), initial fill volume (205.6 ± 133.1 mL vs. 90.4 ± 51.4 mL; p < 0.001), and initial fill ratio (39.3% ± 17.1% vs. 19.5% ± 9.0%; p < 0.001). Table 1 Patient demographics and clinical characteristics of the prepectoral and subpectoral groups Bold indicates statistical significance (p < 0.05). Expander Placement prepectoral (128patients, 135 breasts) subpectoral (48patients, 52 breasts) p value age (average, SD) 49.1 8.0 50 10.5 p = 0.06 BMI (average, SD) 23.2 3.8 21.8 3.7 p = 0.02 smoking (n) (%) 39 28.9% 13 25% p = 0.72 Comorbidities DM (n) (%) 2 1.5% 1 1.90% p = 1 HTN (n) (%) 1 0.74% 4 7.70% p = 0.02 steroid use(History of corticosteroid use) 0 0% 0 0% Other conditions potentially affecting wound healing 0 0% 0 0% Breast cancer treatment history Surgery 6 4.4% 6 11.54% p = 0.08 Radiotherapy 4 3.0% 3 5.77% p = 0.40 Chemotherapy 0 0.0% 2 3.85% p = 0.08 Endocrine therapy 2 1.5% 3 5.77% p = 0.13 Clinical stage RRM 1 0.7% 1 1.92% p = 0.30 in situ 33 24.4% 8 15.38% I 49 36.3% 26 50.00% II 45 33.3% 16 30.77% III 7 5.2% 1 1.92% IV 0 0% 0 0.00% Neoadjuvant therapy Chemotherapy 24 17.8% 6 11.54% p = 0.38 Endocrine therapy 0 0% 0 0.00% Targeted therapy 11 8.1% 0 0.00% p = 0.03 Surgical procedure nipple sparing mastectomy 66 48.9% 37 71.15% p = 0.02 skin sparing mastectomy 60 44.4% 14 26.92% Total mastecomy 9 6.7% 1 1.92% Mastectomy specimen weight (mean, SD, missing data) 329 188, 52 363 168, 22 p = 0.99 Type of axillary surgery none 2 1.5% 1 1.92% p = 0.41 SLNB 101 74.8% 43 82.69% ALND 32 23.7% 8 15.38% Pathological stage RRM 1 0.7% 1 1.92% p = 0.08 in situ 31 23.0% 10 19.23% I 40 29.6% 26 50.00% II 54 40.0% 12 23.08% III 0 0% 3 5.77% IV 0 0% 0 0.00% Adjuvant therapy Chemotherapy 57 42.2% 15 28.85% p = 0.10 during tissue expansion phase Endocrine therapy 83 61.5% 36 69.23% p = 0.40 Targeted therapy 30 22.2% 4 7.69% p = 0.02 Radiotherapy 7 5.2% 2 3.85% p = 1 TE nominal volume (mL) (average, SD) 497.6 143.2 464.3 146.4 p = 0.16 Initial fill volume (mL) (average, SD) 205.6 133.1 90.4 51.4 p < 0.001 Initial fill ratio (% of nominal volume) (average, SD) 39.3% 17.1% 19.5% 9.0% p < 0.001 Postoperative complications are summarized in Table 2 . Nipple-areolar or skin necrosis occurred in 10 breasts (7.4%) in the prepectoral group and 6 breasts (11.5%) in the subpectoral group (p = 0.39). Most cases in the prepectoral group (9 of 10) were treated surgically, while conservative treatment was more common in the subpectoral group (5 of 6). TE removal due to necrosis was required in 2 prepectoral and 1 subpectoral cases. Infections unrelated to skin or nipple necrosis were observed in 17 breasts (13.3%) in the prepectoral group and 1 breast (2.2%) in the subpectoral group (p = 0.03). The mean time to infection onset was 68.2 days (range: 15–262) in the prepectoral group and 46 days in the subpectoral group. In the prepectoral group, 14 cases required invasive interventions such as incision or continuous irrigation, with 10 of these resulting in TE removal or unplanned early autologous reconstruction. Seroma without infection occurred in 21 breasts (15.6%) in the prepectoral group and 1 breast (1.9%) in the subpectoral group (p = 0.01). The mean onset was 20.6 days postoperatively (range: 2–42). In the prepectoral group, seromas were aspirated an average of 2.3 times (range: 1–6), with a mean total aspirated volume of 121 mL (range: 10–370 mL). TE exposure without associated infection or necrosis occurred in 5 breasts (4.6%) in the prepectoral group and in none of the subpectoral cases. The mean time to exposure was 182 days (range: 28–447). Of these, 3 cases required TE removal and 2 underwent early flap reconstruction. Other complications included 2 cases of hematoma (1.5%) in the prepectoral group, one of which led to TE removal and the other was followed by seroma. Total expansion failure occurred in 17 breasts (13.6%) in the prepectoral group and 2 breasts (3.8%) in the subpectoral group. Table 2 Postoperative complications in the prepectoral and subpectoral groups expander placement prepectoral (128patients, 135 breasts) subpectoral (48patients, 52 breasts) p value nipple/ skin ischemia 10 (7.4%) 6 (11.5%) 0.39 nipple 7 6 skin 3 0 Treatment provided Conservative treatment (e.g., ointment application) 1 1 recovery 5 4 recovery 1 infection f/b flap reconstruction Debridement of necrotic tissue 9 7 recovery 1 1 recovery 2 TE removal (1 infection, 1 wound dehiscence) Infection without skin/ nipple necrosis 17 (13.3%) 1 (2.2%) 0.03 time to onset (day) (mean, (range)) 68.2 (15–262) 46 Treatment provided Invasive intervention (e.g., incision, continuous drainage) 14 3 recovery 5 prompt flap reconstruction 5 TE removal 0 Non-invasive intervention (e.g., antibiotic therapy, needle aspiration) 3 3 recovery 1 1 TE removal Seroma without infection 21 (15.6%) 1 (1.9%) 0.01 time to onset (day) (mean, (range)) 20.6 (2–42) (mean, (range)) 55 number of needle aspiration (mean, (range)) 2.3 ( 1 – 6 ) (mean, (range)) 1 total aspirated fluid volume (mL) (mean, (range)) 121(10–370) (mean, (range)) 15 Tissue expander exposure without infection or nipple/skin necrosis 5 (4.6%) 3 TE removal 2 prompt flap reconstrustion 0 (0%) time to onset (day) 182(28–447) (mean, (range)) Other complications hematoma 2 (1.5%) 0 (0%) 1 removal, 1 f/b seroma Total expansion fault 17 (13.6%) 2 (3.8%) Bold indicates statistical significance (p < 0.05). Factors associated with infection and seroma are shown in Table 3 . For infection, univariate analysis revealed significant associations with TE placement plane (p = 0.03) and final fill ratio (p < 0.01), while age approached significance (p = 0.07). For seroma, TE placement plane (p = 0.01) and neoadjuvant targeted therapy (p = 0.03) were significant. Multivariate logistic regression for infection included TE placement plane (prepectoral vs. subpectoral), final fill ratio (< 0.6 vs. ≥0.6), and age (≥ 50 vs. <50). Subpectoral placement was independently associated with lower odds of infection (OR = 12.0; 95% CI: 1.42–102.0; p = 0.03), and a final fill ratio < 0.6 also showed a strong association (OR = 9.94; 95% CI: 2.98–33.1; p < 0.001). Age was excluded from the final model. For seroma, the regression model included TE placement plane, total TE volume (≥ 545 mL vs. <545 mL), and neoadjuvant targeted therapy. Prepectoral placement was the only independent predictor (OR = 9.43; 95% CI: 1.23–71.9; p = 0.01). Neither TE volume nor neoadjuvant targeted therapy reached statistical significance in the final model. For infection, multivariate logistic regression was performed including TE placement plane (subpectoral vs. prepectoral), final fill ratio (< 0.6 vs. ≥0.6), and age (≥ 50 vs. <50). Subpectoral placement was significantly associated with higher odds of infection (OR = 12.0; 95% CI: 1.42–102.0, p = 0.03), and a final fill ratio < 0.6 also showed a strong association (OR = 9.94; 95% CI: 2.98–33.1, p < 0.001). Age did not show a significant association and was excluded from the final model. For seroma, the regression model included TE placement plane, total TE volume (≥ 545 mL vs. <545 mL), and neoadjuvant molecular targeted therapy. Subpectoral placement was associated with significantly lower odds of seroma (OR = 9.43; 95% CI: 1.23–71.9, p = 0.01). Neoadjuvant molecular targeted therapy was associated with a higher incidence of seroma but did not reach statistical significance, nor did TE volume. Table 3 Screening of risk factors for infection and seroma by univariate analysis Complications Infection P-value Seroma P-value Age 0.07 0.66 BMI 0.18 0.17 Smoking 0.59 1 Comorbidities DM 1 1 HTN 1 0.47 Breast cancer treatment history Surgery 0.61 1 Radiotherapy 1 0.59 Chemotherapy 1 1 Endocrine therapy 1 1 Neoadjuvant therapy Chemotherapy 0.18 0.76 Targeted therapy 0.29 0.03 Surgical procedure NSM/ SSM/ Total M 0.64 0.26 Mastectomy specimen weight 0.37 0.31 Type of axillary surgery None/ SLNB/ ALND 0.67 0.71 Pathological stage RRM/ in situ/ I/ II/ III/ IV 0.54 0.84 Adjuvant therapy Chemotherapy 0.45 0.82 during tissue expansion phase Endocrine therapy 1 0.37 Targeted therapy 0.29 0.74 Radiotherapy 1 0.60 TE nominal volume (mL) 0.36 0.06 Initial fill volume (mL) 0.20 0.09 Initial fill ratio (% of nominal volume) 0.10 0.11 Final fill volume (mL) 0.28 0.39 Final fill ratio (% of nominal volume) < 0.01 0.18 Prepectoral/ Subpectoral 0.03 0.01 Bold indicates statistical significance (p < 0.05). Italic values (p < 0.01) were included in multivariate analysis. Discussion This study evaluated postoperative complications following prepectoral and subpectoral TE placement in a Japanese cohort. Compared to subpectoral placement, prepectoral placement was associated with significantly higher rates of infection and seroma, while no significant difference was observed in nipple–areolar or skin necrosis. TE exposure without infection or necrosis occurred exclusively in the prepectoral group. Infection The infection rate unrelated to necrosis was notably higher in the prepectoral group (13.3%) compared to the subpectoral group (2.2%). In the prepectoral group, 14 of 17 infections required invasive interventions such as incision and drainage or continuous irrigation, and 10 of these cases ultimately led to TE removal or unplanned early autologous reconstruction. These complications often resulted in suboptimal outcomes, including skin paddle exposure or limited breast volume, due to insufficient expansion and excision of necrotic tissue. The sole infection in the subpectoral group was initially managed conservatively but eventually required TE removal. Infections were categorized as either associated with necrosis or occurring independently, in order to better understand their nature and underlying mechanisms. Most infections in the prepectoral group developed without overt necrosis and occurred relatively late, with a mean onset of 68.2 days. These findings suggest that such infections may reflect soft tissue vulnerability or implant-related factors, rather than wound dehiscence. In a retrospective study by Long et al.( 7 ), infection occurred in 22 of 440 subpectoral reconstructions (5.0%) and 4 of 22 subcutaneous reconstructions (18.2%). Although no statistical comparison was provided in their report, Fisher’s exact test applied to these numbers yields a p-value of 0.042, supporting our finding that prepectoral placement may be associated with a higher risk of infection. One possible explanation for this elevated risk is the presence of residual breast tissue beneath the mastectomy flap. Griepsma et al.( 8 ) examined 206 mastectomy specimens and found that 76.2% contained residual benign breast tissue at the superficial dissection plane, indicating that complete removal of glandular elements is difficult to achieve. Histologic analysis revealed normal ductal structures at inked margins, suggesting that the subcutaneous flap often remains in contact with glandular tissue, which may compromise sterility in prepectoral reconstruction. In addition to implant placement plane, our multivariate analysis identified a final fill ratio < 0.6 as an independent risk factor for infection. However, as this is a post hoc variable, the direction of causality remains unclear. Infection may have resulted from persistent dead space due to limited expansion, as suggested in previous studies,( 9 ) or conversely, infection may have precluded further expansion. Thus, while the association is statistically significant, interpretation requires caution. However, in contrast to our findings, many previous studies have reported no significant difference in infection rates between prepectoral and subpectoral reconstruction.( 4 , 10 , 11 ) These reports have predominantly come from Western countries, and data from Japan or East Asia remain limited. One potential explanation for the discrepancy between our findings and previous reports lies in differences in mastectomy flap thickness. Several studies have suggested that thicker flaps are associated with lower rates of ischemic complications and infection, likely due to better perfusion and more robust soft-tissue coverage of the implant or expander.( 12 , 13 ) In Japan, thinner mastectomy flaps are frequently observed, possibly due to lower BMI and distinct surgical approaches, as described by Ishii et al.( 14 ), though no direct comparative data exist. Although no studies have directly compared mastectomy flap thickness between Japanese and Western patients, it is possible that Japanese breast surgeons tend to perform wider resections to ensure oncological safety. This interpretation is further supported by a report showing a remarkably low 5-year local recurrence rate of 0.6% among Japanese breast cancer patients, which is substantially lower than the 3–6% typically reported in Western populations (Park et al., 2011). This difference may reflect a more aggressive surgical approach in Japan, which, while potentially oncologically beneficial, could result in thinner flaps and increased risk of complications in prepectoral reconstruction.( 15 ) Furthermore, unlike many Western studies where acellular dermal matrix (ADM) is routinely used to support the implant and reinforce the soft-tissue envelope( 4 , 10 ), ADM is not currently approved for clinical use in Japan. This lack of ADM availability may further contribute to the higher complication rates observed in prepectoral reconstruction in the Japanese setting. Seroma Seroma occurred significantly more frequently in the prepectoral group (15.6% vs. 1.9%), requiring multiple aspirations typically with higher fluid volumes. Persistent seroma has been reported as a potential risk factor for subsequent infection or implant exposure due to fluid accumulation and impaired tissue healing ( 9 , 16 ). However, no cases of infection or TE exposure were directly attributable to seroma in the present study. In the present study, fluid collections were classified as “infection” if the aspirated fluid was turbid, cultures were positive, or if the attending physician made a clinical diagnosis of infection. Only collections without such features were classified as seroma. In the prepectoral group, seroma typically developed at a mean of 20.6 days postoperatively, while infection occurred significantly later, with a mean onset of 68.2 days. This temporal separation, combined with our strict diagnostic criteria, supports the interpretation that seroma and infection were distinct complications in this cohort, rather than part of a continuous pathological process. This distinction may also explain discrepancies in prior studies, where diagnostic criteria for seroma and infection were often undefined or inconsistent. Exposure Although TE exposure was not statistically significant between groups, it occurred exclusively in the prepectoral group (4.6%) and was absent in the subpectoral group. This may reflect mechanical vulnerability of the mastectomy skin flap lacking muscular support, particularly in patients with thinner flaps. While the difference did not reach statistical significance, the small sample size (5 cases vs. 0) raises the possibility that a significant difference could emerge with a larger cohort. In a meta-analysis by Abbate et al.( 10 ), ADM was used for anterior coverage in most studies involving prepectoral reconstruction, yet no significant difference in device exposure was observed between the two approaches. These findings suggest that the additional soft-tissue support provided by ADM may help mitigate the risk of exposure, particularly in prepectoral reconstruction. In contrast, ADM was not utilized in our series, and the presence of unreinforced mastectomy skin flaps may have contributed to the TE exposure observed in the prepectoral group. In addition, as discussed above, thinner mastectomy flaps in the Japanese population may also contribute to increased vulnerability in prepectoral reconstruction without muscular or ADM reinforcement. Multivariate logistic regression analysis identified implant placement plane and final fill ratio as independent predictors of infection. Prepectoral placement and a final fill ratio below 0.6 were both associated with significantly higher odds of infection, although the latter may reflect reverse causality and should be interpreted with caution. For seroma, prepectoral placement was the only significant risk factor retained in the final model, indicating a strong association between this approach and postoperative fluid accumulation. Although TE exposure did not reach statistical significance between groups, all cases occurred in the prepectoral group. Although the number of exposure events was small and statistical comparison was limited, their exclusive occurrence in the prepectoral group raises concern about flap vulnerability without muscular or ADM support. These findings collectively suggest that implant placement plane plays a central role in the development of major complications following immediate breast reconstruction and should be carefully considered when selecting surgical strategy. In cases of skin or nipple–areola complex (NAC) necrosis, the management strategy may differ significantly depending on the reconstruction plane. In subpectoral reconstruction, the underlying pectoralis major muscle provides vascularized tissue support, which can allow for conservative management of minor skin necrosis in selected cases. This is likely due to the added vascular support and mechanical protection provided by the muscle layer in subpectoral reconstruction. This difference in management approach was also observed in our cohort: in the prepectoral group, most cases of skin necrosis required surgical intervention, whereas conservative management was more often feasible in the subpectoral group. This study provides important preliminary data relevant to clinical practice in Japan, where prepectoral placement of silicone breast implants (SBIs) remains unapproved and clinical evidence is scarce. Because prepectoral TE placement is currently permitted in immediate two-stage reconstruction intended for autologous conversion, evaluating outcomes under these conditions may help inform future decisions. These include regulatory approvals and clinical guidelines for potential SBI use. The findings of this study may not be directly applicable to SBI placement, as tissue expanders differ structurally and functionally from implants. Specifically, they leave more dead space during early healing, which may increase the risk of seroma and infection. The higher rates of infection and TE exposure observed in our prepectoral group contrast with several Western studies reporting comparable complication rates between reconstruction planes.( 4 , 10 ) This discrepancy may reflect anatomical and procedural differences specific to Japan, including thinner and less vascularized mastectomy flaps, lower patient BMI( 14 ), and the unavailability of acellular dermal matrix (ADM) for soft-tissue support.( 10 ) Given that both infection and exposure can compromise reconstructive outcomes and aesthetic results, these risks must be carefully weighed when considering the adoption of prepectoral techniques under current Japanese conditions. Limitations This study has several limitations. First, it was conducted at a single institution, which may limit the generalizability of the findings. Second, the retrospective design and relatively short follow-up period preclude assessment of long-term outcomes such as capsular contracture or delayed implant loss. Third, the diagnosis of infection was based on clinical judgment by the attending surgeon, supported by aspirate characteristics or culture results, which may introduce interobserver variability. In addition, although the choice of TE placement was influenced by intraoperative evaluation—favoring subpectoral placement in cases with thin or compromised mastectomy flaps—the infection rate remained higher in the prepectoral group. This suggests that the observed difference may not be attributable to selection bias and may, in fact, be a conservative estimate of the true risk associated with prepectoral placement under current clinical conditions. Furthermore, the number of TE exposure events was small, which limits the statistical power to detect significant differences between groups. As such, the true risk of exposure in prepectoral reconstruction may have been underestimated. Finally, as this study evaluated outcomes using tissue expanders, the findings may not be directly generalizable to silicone breast implants. Conclusion This study provides preliminary evidence suggesting that prepectoral TE placement following mastectomy in Japanese patients is associated with higher rates of infection, seroma, and TE exposure compared to subpectoral placement. While seroma formation may be inherent to the nature of tissue expanders, the observed differences in infection and exposure highlight the need for careful patient selection and surgical planning. These findings underscore the importance of considering patient body habitus and mastectomy skin flap thickness when evaluating prepectoral reconstruction approaches in Japanese clinical practice. These data may serve as a foundation for future prospective, multicenter studies evaluating the safety and indications of prepectoral implant-based reconstruction in Japan. Such efforts will be essential for establishing guidelines tailored to the anatomical and procedural characteristics unique to Japanese patients, thereby supporting safer and more effective implant-based reconstruction in Japan. Declarations Ethics approval: This study was approved by the Institutional Review Board of St. Marianna University (Approval No. 6904(B97)). Informed consent: Informed consent was obtained by an opt-out approach, as information about this study was disclosed on the institution's website in accordance with ethical guidelines. Conflict of interest: The authors declare no conflicts of interest. 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Breast Cancer Res Treat. 2020;182(3):543–54. Limido E, Bonomi F, Guggenheim L, Peradze N, Parodi C, Schmauss D et al. First experience from 200 cases with a new breast tissue expander for multi-stage pre-pectoral breast reconstruction after mastectomy. J Plast Reconstr Aesthet Surg [Internet]. 2025; Available from: http://dx.doi.org/10.1016/j.bjps.2025.06.007 Frey JD, Salibian AA, Choi M, Karp NS. Mastectomy flap thickness and complications in nipple-sparing mastectomy: Objective evaluation using magnetic resonance imaging. Plast Reconstr Surg Glob Open. 2017;5(8):e1439. Najmiddinov B, Park JK-H, Yoon K-H, Myung Y, Koh HW, Lee OH, et al. Conventional versus modified nipple sparing mastectomy in immediate breast reconstruction: Complications, aesthetic, and patient-reported outcomes. Front Surg. 2022;9:1001019. Ishii N. Current status of pre- or subpectoral breast reconstruction in Japan. Gland Surg. 2023;12(12):1786–93. Park Y, Kitahara T, Takagi R, Kato R. Current status of therapy for breast cancer worldwide and in Japan. World J Clin Oncol. 2011;2(2):125–34. Jordan SW, Khavanin N, Kim JYS. Seroma in prosthetic breast reconstruction. Plast Reconstr Surg. 2016;137(4):1104–16. Cite Share Download PDF Status: Published Journal Publication published 25 Sep, 2025 Read the published version in Breast Cancer → Version 1 posted Reviewers agreed at journal 14 Jul, 2025 Reviewers invited by journal 14 Jul, 2025 Editor assigned by journal 04 Jul, 2025 First submitted to journal 04 Jul, 2025 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. We do this by developing innovative software and high quality services for the global research community. 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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-7048730","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":485399360,"identity":"9b400527-e8ab-4f5a-b9bb-df097efeed02","order_by":0,"name":"Ryotaro Miyano","email":"","orcid":"","institution":"St Marianna University School of Medicine: Sei Marianna Ika Daigaku","correspondingAuthor":false,"prefix":"","firstName":"Ryotaro","middleName":"","lastName":"Miyano","suffix":""},{"id":485399361,"identity":"51e7dbf0-7e6d-4127-a853-017fcf9aef2a","order_by":1,"name":"Tomohiro Shiraishi","email":"data:image/png;base64,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","orcid":"https://orcid.org/0009-0004-8262-6329","institution":"Kyorin University Faculty of Medicine: Kyorin Daigaku Igakubu Daigakuin Igaku Kenkyuka","correspondingAuthor":true,"prefix":"","firstName":"Tomohiro","middleName":"","lastName":"Shiraishi","suffix":""}],"badges":[],"createdAt":"2025-07-04 17:15:48","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7048730/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7048730/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s12282-025-01784-6","type":"published","date":"2025-09-25T15:58:19+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":92430959,"identity":"45c7d588-6f7e-4d46-b4a4-fce0451384ee","added_by":"auto","created_at":"2025-09-29 16:08:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":937484,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7048730/v1/78f822dc-59ff-4148-bb57-eb076d79ba8c.pdf"}],"financialInterests":"","formattedTitle":"Postoperative Complications Following Prepectoral Versus Subpectoral Tissue Expander Placement in Immediate Breast Reconstruction: A Retrospective Study from Japan","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePrepectoral implant placement has emerged as a significant advancement in implant-based breast reconstruction, offering an alternative to the traditional subpectoral approach.(\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) This technique avoids the subpectoral plane and preserves the pectoralis major muscle, which has been associated with reduced postoperative pain, faster recovery, and elimination of animation deformity compared to traditional subpectoral reconstruction.(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) Several studies from Western countries have demonstrated comparable complication rates between prepectoral and subpectoral approaches, while highlighting the aesthetic and functional benefits of prepectoral reconstruction.(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eIn Japan, however, direct-to-implant (DTI) reconstruction using a prepectoral approach remains unapproved, and prepectoral silicone breast implant (SBI) placement is not yet an established practice. According to the 2023 clinical practice guidelines issued by the Japan Oncoplastic Breast Surgery Society, subpectoral placement is recommended for SBI.(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) As a result, there are currently no clinical data regarding prepectoral SBI placement in Japanese patients. Nonetheless, immediate two-stage reconstruction with prepectoral tissue expander (TE) placement is permitted in cases where autologous reconstruction is planned. Evaluating the complications associated with prepectoral TE placement may provide critical preliminary evidence to inform the future adoption of prepectoral SBI placement in Japan. This study aimed to retrospectively compare postoperative complication rates between prepectoral and subpectoral TE placement in a Japanese cohort, focusing on infection, seroma, and TE exposure. We hope our findings will contribute to safer and more informed surgical decision-making in breast reconstruction.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e We retrospectively reviewed the medical records of patients who underwent mastectomy followed by immediate two-stage breast reconstruction with TE placement between January 2023 and December 2024. Patients were categorized into two groups according to the TE placement plane: prepectoral or subpectoral. Data were collected from clinical records, including patient characteristics: age, body mass index (BMI), smoking status, comorbidities such as diabetes mellitus (DM), hypertension (HTN), corticosteroid use, and other conditions potentially affecting wound healing; prior breast cancer history and treatments (surgery, chemotherapy, hormone therapy, targeted therapy, radiation); current cancer clinical stage; presence and type of neoadjuvant therapy; surgical procedure (nipple-sparing mastectomy [NSM], skin-sparing mastectomy [SSM], or total mastectomy [TM]); mastectomy specimen weight; type of axillary surgery (none, sentinel lymph node biopsy [SLNB], axillary lymph node dissection [ALND]); breast surgeon; reconstructive surgeon; type and size of TE; initial fill volume; initial fill ratio (% of nominal volume);final fill volume; final fill ratio (% of nominal volume) pathological stage; and adjuvant therapy administered during TE expansion. A total of 18 breast surgeons and 23 plastic surgeons were involved in the surgeries; due to the large number of operators, analysis by individual surgeon was not performed. This study was approved by the Institutional Review Board of St. Marianna Unversity (Approval No. 6904(B97))\u003c/p\u003e\u003cp\u003eTE placement was determined based on reconstruction plans: prepectoral placement was selected in patients scheduled for subsequent autologous reconstruction, whereas subpectoral placement was used in patients planning implant-based reconstruction or undecided between the two options. In patients initially scheduled for prepectoral placement, conversion to subpectoral placement was performed intraoperatively if the mastectomy flap was judged to be too thin. In subpectoral reconstruction, the tissue expander was fully covered whenever possible with the pectoralis major muscle and supplemented by additional soft tissue such as the serratus anterior or its fascia to ensure adequate coverage. Two drains were inserted into the subcutaneous space in the prepectoral group. In the subpectoral group, one drain was placed under the pectoralis major muscle, and an additional axillary drain was inserted when axillary dissection was performed. Drains were removed once output was \u0026lt;\u0026thinsp;30 mL/day; antibiotics were continued until drain removal.\u003c/p\u003e\u003cp\u003ePostoperative complications were reviewed for type, timing, treatment, and clinical course. Infection was considered present if the attending surgeon initiated antibiotic treatment based on clinical signs, characteristics of aspirated fluid, or if wound culture results were positive, as documented in the medical record. Univariate analyses were performed using t-tests for continuous variables and Fisher\u0026rsquo;s exact test for categorical variables. Multivariate logistic regression was conducted for complications with significant group differences to identify independent predictors. Variables were selected based on p\u0026thinsp;\u0026lt;\u0026thinsp;0.1 in univariate analysis and the number of events. For continuous variables without established clinical thresholds, cutoff values were determined using receiver operating characteristic (ROC) curve analysis based on the Youden index. The optimal cutoff for age by ROC analysis was 51 years; however, a cutoff of 50 years was used in the final model to improve clinical interpretability and ensure modeling stability. Although older adults are typically defined as \u0026ge;\u0026thinsp;65 years, only 8 patients (9 breasts) were aged 65 or older, while 88 patients (93 breasts) were aged 50 or older; therefore, 50 years was considered a more practical threshold for stratification. All statistical analyses were performed using EZR version 1.52 (Saitama Medical Center, Jichi Medical University, Saitama, Japan), which is a graphical user interface for R version 4.02 (The R Foundation for Statistical Computing, Vienna, Austria).(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e) More precisely, it is a modified version of R commander designed to add statistical functions frequently used in biostatistics. Statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 128 patients (135 breasts) underwent prepectoral TE placement, while 48 patients (52 breasts) received subpectoral placement. Patient characteristics are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Significant differences between the groups were observed in BMI (prepectoral: 23.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8 vs. subpectoral: 21.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7; p\u0026thinsp;=\u0026thinsp;0.02), history of hypertension (0.74% vs. 7.7%; p\u0026thinsp;=\u0026thinsp;0.02), use of neoadjuvant targeted therapy (8.1% vs. 0%; p\u0026thinsp;=\u0026thinsp;0.03), surgical procedure (NSM: 48.9% vs. 71.2%; p\u0026thinsp;=\u0026thinsp;0.02), initial fill volume (205.6\u0026thinsp;\u0026plusmn;\u0026thinsp;133.1 mL vs. 90.4\u0026thinsp;\u0026plusmn;\u0026thinsp;51.4 mL; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and initial fill ratio (39.3% \u0026plusmn; 17.1% vs. 19.5% \u0026plusmn; 9.0%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\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\u003ePatient demographics and clinical characteristics of the prepectoral and subpectoral groups Bold indicates statistical significance (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\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\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExpander Placement\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eprepectoral (128patients, 135 breasts)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003esubpectoral (48patients, 52 breasts)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eage (average, SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e49.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e10.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBMI (average, SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e21.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u0026thinsp;=\u0026thinsp;0.02\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003esmoking (n) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e28.9%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e25%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.72\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComorbidities\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDM (n) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.90%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHTN (n) (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.74%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e7.70%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u0026thinsp;=\u0026thinsp;0.02\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003esteroid use(History of corticosteroid use)\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\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOther conditions potentially affecting wound healing\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\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBreast cancer treatment history\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSurgery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4.4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11.54%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.08\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRadiotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.77%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChemotherapy\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\u003e0.0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.85%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.08\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEndocrine therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.77%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.13\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eClinical stage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRRM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.7%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.92%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.30\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ein situ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e24.4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e15.38%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e36.3%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e50.00%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eII\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e33.3%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e30.77%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIII\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.92%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIV\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\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.00%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNeoadjuvant therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChemotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e17.8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11.54%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.38\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEndocrine therapy\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\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.00%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTargeted therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8.1%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.00%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u0026thinsp;=\u0026thinsp;0.03\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSurgical procedure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003enipple sparing mastectomy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e48.9%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e71.15%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u0026thinsp;=\u0026thinsp;0.02\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eskin sparing mastectomy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e44.4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e26.92%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTotal mastecomy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.7%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.92%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMastectomy specimen weight\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(mean, SD, missing data)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e329\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e188, 52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e363\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e168, 22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.99\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eType of axillary surgery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003enone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.92%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.41\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSLNB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e101\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e74.8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e82.69%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eALND\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e23.7%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e15.38%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePathological stage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRRM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.7%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.92%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.08\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ein situ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e23.0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e19.23%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e29.6%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e50.00%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eII\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\u003e40.0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e23.08%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIII\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\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.77%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIV\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\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.00%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAdjuvant therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChemotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e42.2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e28.85%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eduring tissue expansion phase\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEndocrine therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e61.5%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e69.23%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTargeted therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e22.2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e7.69%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u0026thinsp;=\u0026thinsp;0.02\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRadiotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.85%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTE\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003enominal volume (mL) (average, SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e497.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e143.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e464.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e146.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial fill volume (mL) (average, SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e205.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e133.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e90.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e51.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial fill ratio (% of nominal volume) (average, SD)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e39.3%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e17.1%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e19.5%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9.0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/b\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\u003ePostoperative complications are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Nipple-areolar or skin necrosis occurred in 10 breasts (7.4%) in the prepectoral group and 6 breasts (11.5%) in the subpectoral group (p\u0026thinsp;=\u0026thinsp;0.39). Most cases in the prepectoral group (9 of 10) were treated surgically, while conservative treatment was more common in the subpectoral group (5 of 6). TE removal due to necrosis was required in 2 prepectoral and 1 subpectoral cases. Infections unrelated to skin or nipple necrosis were observed in 17 breasts (13.3%) in the prepectoral group and 1 breast (2.2%) in the subpectoral group (p\u0026thinsp;=\u0026thinsp;0.03). The mean time to infection onset was 68.2 days (range: 15\u0026ndash;262) in the prepectoral group and 46 days in the subpectoral group. In the prepectoral group, 14 cases required invasive interventions such as incision or continuous irrigation, with 10 of these resulting in TE removal or unplanned early autologous reconstruction. Seroma without infection occurred in 21 breasts (15.6%) in the prepectoral group and 1 breast (1.9%) in the subpectoral group (p\u0026thinsp;=\u0026thinsp;0.01). The mean onset was 20.6 days postoperatively (range: 2\u0026ndash;42). In the prepectoral group, seromas were aspirated an average of 2.3 times (range: 1\u0026ndash;6), with a mean total aspirated volume of 121 mL (range: 10\u0026ndash;370 mL). TE exposure without associated infection or necrosis occurred in 5 breasts (4.6%) in the prepectoral group and in none of the subpectoral cases. The mean time to exposure was 182 days (range: 28\u0026ndash;447). Of these, 3 cases required TE removal and 2 underwent early flap reconstruction. Other complications included 2 cases of hematoma (1.5%) in the prepectoral group, one of which led to TE removal and the other was followed by seroma. Total expansion failure occurred in 17 breasts (13.6%) in the prepectoral group and 2 breasts (3.8%) in the subpectoral group.\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\u003ePostoperative complications in the prepectoral and subpectoral 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=\"left\" 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=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eexpander placement\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003eprepectoral (128patients, 135 breasts)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003esubpectoral (48patients, 52 breasts)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003ep value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003enipple/ skin ischemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e10 (7.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003e6 (11.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003enipple\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eskin\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatment provided\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eConservative treatment\u003c/p\u003e\u003cp\u003e(e.g., ointment application)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 recovery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e4 recovery\u003c/p\u003e\u003cp\u003e1 infection f/b flap reconstruction\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDebridement of necrotic tissue\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7 recovery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 recovery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\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=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2 TE removal\u003c/p\u003e\u003cp\u003e(1 infection, 1 wound dehiscence)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eInfection without skin/ nipple necrosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e17 (13.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003e1 (2.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u003cb\u003e0.03\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003etime to onset (day)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e68.2 (15\u0026ndash;262)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatment provided\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInvasive intervention\u003c/p\u003e\u003cp\u003e(e.g., incision, continuous drainage)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3 recovery\u003c/p\u003e\u003cp\u003e5 prompt flap reconstruction\u003c/p\u003e\u003cp\u003e5 TE removal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNon-invasive intervention\u003c/p\u003e\u003cp\u003e(e.g., antibiotic therapy, needle aspiration)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3 recovery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 TE removal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eSeroma without infection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e21 (15.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003e1 (1.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003etime to onset (day)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e20.6 (2\u0026ndash;42) (mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003enumber of needle aspiration (mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2.3 (\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e) (mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003etotal aspirated fluid volume (mL) (mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e121(10\u0026ndash;370) (mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eTissue expander exposure without infection or nipple/skin necrosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e5 (4.6%)\u003c/p\u003e\u003cp\u003e3 TE removal\u003c/p\u003e\u003cp\u003e2 prompt flap reconstrustion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003e0 (0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003etime to onset\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(day)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e182(28\u0026ndash;447) (mean, (range))\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOther complications\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=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ehematoma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e2 (1.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003e0 (0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\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=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 removal, 1 f/b seroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal expansion fault\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e17 (13.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e\u003cp\u003e2 (3.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"9\"\u003eBold indicates statistical significance (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eFactors associated with infection and seroma are shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. For infection, univariate analysis revealed significant associations with TE placement plane (p\u0026thinsp;=\u0026thinsp;0.03) and final fill ratio (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), while age approached significance (p\u0026thinsp;=\u0026thinsp;0.07). For seroma, TE placement plane (p\u0026thinsp;=\u0026thinsp;0.01) and neoadjuvant targeted therapy (p\u0026thinsp;=\u0026thinsp;0.03) were significant. Multivariate logistic regression for infection included TE placement plane (prepectoral vs. subpectoral), final fill ratio (\u0026lt;\u0026thinsp;0.6 vs. \u0026ge;0.6), and age (\u0026ge;\u0026thinsp;50 vs. \u0026lt;50). Subpectoral placement was independently associated with lower odds of infection (OR\u0026thinsp;=\u0026thinsp;12.0; 95% CI: 1.42\u0026ndash;102.0; p\u0026thinsp;=\u0026thinsp;0.03), and a final fill ratio\u0026thinsp;\u0026lt;\u0026thinsp;0.6 also showed a strong association (OR\u0026thinsp;=\u0026thinsp;9.94; 95% CI: 2.98\u0026ndash;33.1; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Age was excluded from the final model. For seroma, the regression model included TE placement plane, total TE volume (\u0026ge;\u0026thinsp;545 mL vs. \u0026lt;545 mL), and neoadjuvant targeted therapy. Prepectoral placement was the only independent predictor (OR\u0026thinsp;=\u0026thinsp;9.43; 95% CI: 1.23\u0026ndash;71.9; p\u0026thinsp;=\u0026thinsp;0.01). Neither TE volume nor neoadjuvant targeted therapy reached statistical significance in the final model. For infection, multivariate logistic regression was performed including TE placement plane (subpectoral vs. prepectoral), final fill ratio (\u0026lt;\u0026thinsp;0.6 vs. \u0026ge;0.6), and age (\u0026ge;\u0026thinsp;50 vs. \u0026lt;50). Subpectoral placement was significantly associated with higher odds of infection (OR\u0026thinsp;=\u0026thinsp;12.0; 95% CI: 1.42\u0026ndash;102.0, p\u0026thinsp;=\u0026thinsp;0.03), and a final fill ratio\u0026thinsp;\u0026lt;\u0026thinsp;0.6 also showed a strong association (OR\u0026thinsp;=\u0026thinsp;9.94; 95% CI: 2.98\u0026ndash;33.1, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Age did not show a significant association and was excluded from the final model. For seroma, the regression model included TE placement plane, total TE volume (\u0026ge;\u0026thinsp;545 mL vs. \u0026lt;545 mL), and neoadjuvant molecular targeted therapy. Subpectoral placement was associated with significantly lower odds of seroma (OR\u0026thinsp;=\u0026thinsp;9.43; 95% CI: 1.23\u0026ndash;71.9, p\u0026thinsp;=\u0026thinsp;0.01). Neoadjuvant molecular targeted therapy was associated with a higher incidence of seroma but did not reach statistical significance, nor did TE volume.\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\u003eScreening of risk factors for infection and seroma by univariate analysis\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\u003eComplications\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eInfection\u003c/p\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSeroma\u003c/p\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003e0.07\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.66\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBMI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSmoking\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComorbidities\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHTN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.47\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBreast cancer treatment history\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSurgery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRadiotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.59\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChemotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEndocrine therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNeoadjuvant therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChemotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.76\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTargeted therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.03\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSurgical procedure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNSM/ SSM/ Total M\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMastectomy specimen weight\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.31\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eType of axillary surgery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNone/ SLNB/ ALND\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.71\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePathological stage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRRM/ in situ/ I/ II/ III/ IV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.84\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAdjuvant therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChemotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.82\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eduring tissue expansion phase\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEndocrine therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTargeted therapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.74\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRadiotherapy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.60\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTE\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003enominal volume (mL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003e0.06\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial fill volume (mL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.09\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInitial fill ratio (% of nominal volume)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.11\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFinal fill volume (mL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFinal fill ratio (% of nominal volume)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePrepectoral/ Subpectoral\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e0.03\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eBold indicates statistical significance (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eItalic values (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) were included in multivariate analysis.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study evaluated postoperative complications following prepectoral and subpectoral TE placement in a Japanese cohort. Compared to subpectoral placement, prepectoral placement was associated with significantly higher rates of infection and seroma, while no significant difference was observed in nipple\u0026ndash;areolar or skin necrosis. TE exposure without infection or necrosis occurred exclusively in the prepectoral group.\u003c/p\u003e\u003cp\u003e\u003cem\u003eInfection\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThe infection rate unrelated to necrosis was notably higher in the prepectoral group (13.3%) compared to the subpectoral group (2.2%). In the prepectoral group, 14 of 17 infections required invasive interventions such as incision and drainage or continuous irrigation, and 10 of these cases ultimately led to TE removal or unplanned early autologous reconstruction. These complications often resulted in suboptimal outcomes, including skin paddle exposure or limited breast volume, due to insufficient expansion and excision of necrotic tissue. The sole infection in the subpectoral group was initially managed conservatively but eventually required TE removal. Infections were categorized as either associated with necrosis or occurring independently, in order to better understand their nature and underlying mechanisms. Most infections in the prepectoral group developed without overt necrosis and occurred relatively late, with a mean onset of 68.2 days. These findings suggest that such infections may reflect soft tissue vulnerability or implant-related factors, rather than wound dehiscence.\u003c/p\u003e\u003cp\u003eIn a retrospective study by Long et al.(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e), infection occurred in 22 of 440 subpectoral reconstructions (5.0%) and 4 of 22 subcutaneous reconstructions (18.2%). Although no statistical comparison was provided in their report, Fisher\u0026rsquo;s exact test applied to these numbers yields a p-value of 0.042, supporting our finding that prepectoral placement may be associated with a higher risk of infection. One possible explanation for this elevated risk is the presence of residual breast tissue beneath the mastectomy flap. Griepsma et al.(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) examined 206 mastectomy specimens and found that 76.2% contained residual benign breast tissue at the superficial dissection plane, indicating that complete removal of glandular elements is difficult to achieve. Histologic analysis revealed normal ductal structures at inked margins, suggesting that the subcutaneous flap often remains in contact with glandular tissue, which may compromise sterility in prepectoral reconstruction. In addition to implant placement plane, our multivariate analysis identified a final fill ratio\u0026thinsp;\u0026lt;\u0026thinsp;0.6 as an independent risk factor for infection. However, as this is a post hoc variable, the direction of causality remains unclear. Infection may have resulted from persistent dead space due to limited expansion, as suggested in previous studies,(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e) or conversely, infection may have precluded further expansion. Thus, while the association is statistically significant, interpretation requires caution.\u003c/p\u003e\u003cp\u003eHowever, in contrast to our findings, many previous studies have reported no significant difference in infection rates between prepectoral and subpectoral reconstruction.(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) These reports have predominantly come from Western countries, and data from Japan or East Asia remain limited. One potential explanation for the discrepancy between our findings and previous reports lies in differences in mastectomy flap thickness. Several studies have suggested that thicker flaps are associated with lower rates of ischemic complications and infection, likely due to better perfusion and more robust soft-tissue coverage of the implant or expander.(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e) In Japan, thinner mastectomy flaps are frequently observed, possibly due to lower BMI and distinct surgical approaches, as described by Ishii et al.(\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), though no direct comparative data exist. Although no studies have directly compared mastectomy flap thickness between Japanese and Western patients, it is possible that Japanese breast surgeons tend to perform wider resections to ensure oncological safety. This interpretation is further supported by a report showing a remarkably low 5-year local recurrence rate of 0.6% among Japanese breast cancer patients, which is substantially lower than the 3\u0026ndash;6% typically reported in Western populations (Park et al., 2011). This difference may reflect a more aggressive surgical approach in Japan, which, while potentially oncologically beneficial, could result in thinner flaps and increased risk of complications in prepectoral reconstruction.(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e) Furthermore, unlike many Western studies where acellular dermal matrix (ADM) is routinely used to support the implant and reinforce the soft-tissue envelope(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e), ADM is not currently approved for clinical use in Japan. This lack of ADM availability may further contribute to the higher complication rates observed in prepectoral reconstruction in the Japanese setting.\u003c/p\u003e\u003cp\u003e\u003cem\u003eSeroma\u003c/em\u003e\u003c/p\u003e\u003cp\u003eSeroma occurred significantly more frequently in the prepectoral group (15.6% vs. 1.9%), requiring multiple aspirations typically with higher fluid volumes. Persistent seroma has been reported as a potential risk factor for subsequent infection or implant exposure due to fluid accumulation and impaired tissue healing (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). However, no cases of infection or TE exposure were directly attributable to seroma in the present study. In the present study, fluid collections were classified as \u0026ldquo;infection\u0026rdquo; if the aspirated fluid was turbid, cultures were positive, or if the attending physician made a clinical diagnosis of infection. Only collections without such features were classified as seroma. In the prepectoral group, seroma typically developed at a mean of 20.6 days postoperatively, while infection occurred significantly later, with a mean onset of 68.2 days. This temporal separation, combined with our strict diagnostic criteria, supports the interpretation that seroma and infection were distinct complications in this cohort, rather than part of a continuous pathological process. This distinction may also explain discrepancies in prior studies, where diagnostic criteria for seroma and infection were often undefined or inconsistent.\u003c/p\u003e\u003cp\u003e\u003cem\u003eExposure\u003c/em\u003e\u003c/p\u003e\u003cp\u003eAlthough TE exposure was not statistically significant between groups, it occurred exclusively in the prepectoral group (4.6%) and was absent in the subpectoral group. This may reflect mechanical vulnerability of the mastectomy skin flap lacking muscular support, particularly in patients with thinner flaps. While the difference did not reach statistical significance, the small sample size (5 cases vs. 0) raises the possibility that a significant difference could emerge with a larger cohort. In a meta-analysis by Abbate et al.(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e), ADM was used for anterior coverage in most studies involving prepectoral reconstruction, yet no significant difference in device exposure was observed between the two approaches. These findings suggest that the additional soft-tissue support provided by ADM may help mitigate the risk of exposure, particularly in prepectoral reconstruction. In contrast, ADM was not utilized in our series, and the presence of unreinforced mastectomy skin flaps may have contributed to the TE exposure observed in the prepectoral group. In addition, as discussed above, thinner mastectomy flaps in the Japanese population may also contribute to increased vulnerability in prepectoral reconstruction without muscular or ADM reinforcement.\u003c/p\u003e\u003cp\u003eMultivariate logistic regression analysis identified implant placement plane and final fill ratio as independent predictors of infection. Prepectoral placement and a final fill ratio below 0.6 were both associated with significantly higher odds of infection, although the latter may reflect reverse causality and should be interpreted with caution. For seroma, prepectoral placement was the only significant risk factor retained in the final model, indicating a strong association between this approach and postoperative fluid accumulation. Although TE exposure did not reach statistical significance between groups, all cases occurred in the prepectoral group. Although the number of exposure events was small and statistical comparison was limited, their exclusive occurrence in the prepectoral group raises concern about flap vulnerability without muscular or ADM support. These findings collectively suggest that implant placement plane plays a central role in the development of major complications following immediate breast reconstruction and should be carefully considered when selecting surgical strategy.\u003c/p\u003e\u003cp\u003eIn cases of skin or nipple\u0026ndash;areola complex (NAC) necrosis, the management strategy may differ significantly depending on the reconstruction plane. In subpectoral reconstruction, the underlying pectoralis major muscle provides vascularized tissue support, which can allow for conservative management of minor skin necrosis in selected cases. This is likely due to the added vascular support and mechanical protection provided by the muscle layer in subpectoral reconstruction. This difference in management approach was also observed in our cohort: in the prepectoral group, most cases of skin necrosis required surgical intervention, whereas conservative management was more often feasible in the subpectoral group.\u003c/p\u003e\u003cp\u003eThis study provides important preliminary data relevant to clinical practice in Japan, where prepectoral placement of silicone breast implants (SBIs) remains unapproved and clinical evidence is scarce. Because prepectoral TE placement is currently permitted in immediate two-stage reconstruction intended for autologous conversion, evaluating outcomes under these conditions may help inform future decisions. These include regulatory approvals and clinical guidelines for potential SBI use. The findings of this study may not be directly applicable to SBI placement, as tissue expanders differ structurally and functionally from implants. Specifically, they leave more dead space during early healing, which may increase the risk of seroma and infection. The higher rates of infection and TE exposure observed in our prepectoral group contrast with several Western studies reporting comparable complication rates between reconstruction planes.(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e) This discrepancy may reflect anatomical and procedural differences specific to Japan, including thinner and less vascularized mastectomy flaps, lower patient BMI(\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), and the unavailability of acellular dermal matrix (ADM) for soft-tissue support.(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eGiven that both infection and exposure can compromise reconstructive outcomes and aesthetic results, these risks must be carefully weighed when considering the adoption of prepectoral techniques under current Japanese conditions.\u003c/p\u003e\u003cp\u003e\u003cem\u003eLimitations\u003c/em\u003e\u003c/p\u003e\u003cp\u003eThis study has several limitations. First, it was conducted at a single institution, which may limit the generalizability of the findings. Second, the retrospective design and relatively short follow-up period preclude assessment of long-term outcomes such as capsular contracture or delayed implant loss. Third, the diagnosis of infection was based on clinical judgment by the attending surgeon, supported by aspirate characteristics or culture results, which may introduce interobserver variability. In addition, although the choice of TE placement was influenced by intraoperative evaluation\u0026mdash;favoring subpectoral placement in cases with thin or compromised mastectomy flaps\u0026mdash;the infection rate remained higher in the prepectoral group. This suggests that the observed difference may not be attributable to selection bias and may, in fact, be a conservative estimate of the true risk associated with prepectoral placement under current clinical conditions. Furthermore, the number of TE exposure events was small, which limits the statistical power to detect significant differences between groups. As such, the true risk of exposure in prepectoral reconstruction may have been underestimated. Finally, as this study evaluated outcomes using tissue expanders, the findings may not be directly generalizable to silicone breast implants.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study provides preliminary evidence suggesting that prepectoral TE placement following mastectomy in Japanese patients is associated with higher rates of infection, seroma, and TE exposure compared to subpectoral placement. While seroma formation may be inherent to the nature of tissue expanders, the observed differences in infection and exposure highlight the need for careful patient selection and surgical planning. These findings underscore the importance of considering patient body habitus and mastectomy skin flap thickness when evaluating prepectoral reconstruction approaches in Japanese clinical practice.\u003c/p\u003e\u003cp\u003eThese data may serve as a foundation for future prospective, multicenter studies evaluating the safety and indications of prepectoral implant-based reconstruction in Japan. Such efforts will be essential for establishing guidelines tailored to the anatomical and procedural characteristics unique to Japanese patients, thereby supporting safer and more effective implant-based reconstruction in Japan.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval:\u003c/strong\u003e\u003cp\u003eThis study was approved by the Institutional Review Board of St. Marianna University (Approval No. 6904(B97)).\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eInformed consent:\u003c/strong\u003e\u003cp\u003e Informed consent was obtained by an opt-out approach, as information about this study was disclosed on the institution's website in accordance with ethical guidelines.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConflict of interest:\u003c/strong\u003e\u003cp\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\u003ch2\u003eAuthor contributions:\u003c/h2\u003e\u003cp\u003eBoth authors contributed equally to the study design, data analysis, manuscript writing, and final approval of the version to be submitted.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSbitany H. Important considerations for performing prepectoral breast reconstruction. Plast Reconstr Surg. 2017;140:S7\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSigalove S, Maxwell GP, Sigalove NM, Storm-Dickerson TL, Pope N, Rice J, et al. Prepectoral implant-based breast reconstruction: Rationale, indications, and preliminary results. Plast Reconstr Surg. 2017;139(2):287\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePartner E. Procedural Statistics Release.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOstapenko E, Nixdorf L, Devyatko Y, Exner R, Wimmer K, Fitzal F. Prepectoral versus subpectoral implant-based breast reconstruction: A systemic review and meta-analysis. Ann Surg Oncol. 2023;30(1):126\u0026ndash;36.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJapan Oncoplastic Breast Surgery Society. Clinical practice guidelines for breast reconstruction. 2023 edition [Internet]. 2023. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://jopbs.or.jp/medical/guideline/docs/guideline_202304.pdf\u003c/span\u003e\u003cspan address=\"https://jopbs.or.jp/medical/guideline/docs/guideline_202304.pdf\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKanda Y. Investigation of the freely available easy-to-use software EZR for medical statistics. Bone Marrow Transpl. 2013;48(3):452\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLong C, Sue GR, Chattopadhyay A, Huis In\u0026rsquo;t Veld, Lee E. GK. Critical evaluation of risk factors of infection following 2-stage implant-based breast reconstruction. Plast Reconstr Surg Glob Open. 2017;5(7):e1386.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGriepsma M, de Roy DBW, Grond AJK, Siesling S, Groen H, de Bock GH. Residual breast tissue after mastectomy: how often and where is it located? Ann Surg Oncol. 2014;21(4):1260\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAvraham T, Weichman KE, Wilson S, Weinstein A, Haddock NT, Szpalski C, et al. Postoperative expansion is not a primary cause of infection in immediate breast reconstruction with tissue expanders. Breast J. 2015;21(5):501\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAbbate O, Rosado N, Sobti N, Vieira BL, Liao EC. Meta-analysis of prepectoral implant-based breast reconstruction: guide to patient selection and current outcomes. Breast Cancer Res Treat. 2020;182(3):543\u0026ndash;54.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLimido E, Bonomi F, Guggenheim L, Peradze N, Parodi C, Schmauss D et al. First experience from 200 cases with a new breast tissue expander for multi-stage pre-pectoral breast reconstruction after mastectomy. J Plast Reconstr Aesthet Surg [Internet]. 2025; Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.1016/j.bjps.2025.06.007\u003c/span\u003e\u003cspan address=\"10.1016/j.bjps.2025.06.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFrey JD, Salibian AA, Choi M, Karp NS. Mastectomy flap thickness and complications in nipple-sparing mastectomy: Objective evaluation using magnetic resonance imaging. Plast Reconstr Surg Glob Open. 2017;5(8):e1439.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNajmiddinov B, Park JK-H, Yoon K-H, Myung Y, Koh HW, Lee OH, et al. Conventional versus modified nipple sparing mastectomy in immediate breast reconstruction: Complications, aesthetic, and patient-reported outcomes. Front Surg. 2022;9:1001019.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIshii N. Current status of pre- or subpectoral breast reconstruction in Japan. Gland Surg. 2023;12(12):1786\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePark Y, Kitahara T, Takagi R, Kato R. Current status of therapy for breast cancer worldwide and in Japan. World J Clin Oncol. 2011;2(2):125\u0026ndash;34.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJordan SW, Khavanin N, Kim JYS. Seroma in prosthetic breast reconstruction. Plast Reconstr Surg. 2016;137(4):1104\u0026ndash;16.\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":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"breast-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"brca","sideBox":"Learn more about [Breast Cancer](http://link.springer.com/journal/12282)","snPcode":"12282","submissionUrl":"https://www.editorialmanager.com/brca/default2.aspx","title":"Breast Cancer","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7048730/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7048730/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e\u003cbr\u003e\nPrepectoral implant placement has become a widely adopted alternative to subpectoral reconstruction in implant-based breast surgery, offering reduced postoperative pain and improved aesthetic outcomes. However, in Japan, prepectoral placement of silicone breast implants (SBIs) remains unapproved, and its clinical safety has not been well established.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e\u003cbr\u003e\nWe conducted a retrospective review of 176 patients (187 breasts) who underwent immediate two-stage breast reconstruction with tissue expander (TE) placement between January 2023 and December 2024. Patients were categorized into prepectoral (128 patients, 135 breasts) and subpectoral (48 patients, 52 breasts) groups. Postoperative complications including infection, seroma, and TE exposure were compared. Univariate and multivariate logistic regression analyses were performed to identify risk factors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e\u003cbr\u003e\nInfection unrelated to necrosis was more frequent in the prepectoral group (13.3% vs. 2.2%, p = 0.03), with 14 of 17 cases requiring invasive treatment and 10 leading to TE removal or unplanned autologous reconstruction. Seroma occurred in 15.6% of prepectoral cases versus 1.9% of subpectoral (p = 0.01), and TE exposure occurred only in the prepectoral group (4.6%). Multivariate analysis identified prepectoral placement and a final fill ratio \u0026lt;0.6 as independent predictors of infection. Prepectoral placement was also the sole predictor for seroma.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e\u003cbr\u003e\nPrepectoral TE placement in Japanese patients was associated with increased risks of infection, seroma, and TE exposure compared to subpectoral placement. These findings suggest the need for careful patient selection and surgical planning in the context of Japanese clinical practice, where prepectoral SBI use is not yet established.\u003c/p\u003e","manuscriptTitle":"Postoperative Complications Following Prepectoral Versus Subpectoral Tissue Expander Placement in Immediate Breast Reconstruction: A Retrospective Study from Japan","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-17 11:50:05","doi":"10.21203/rs.3.rs-7048730/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-07-15T01:13:21+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-14T22:22:32+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-05T01:06:35+00:00","index":"","fulltext":""},{"type":"submitted","content":"Breast Cancer","date":"2025-07-04T13:15:14+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"breast-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"brca","sideBox":"Learn more about [Breast Cancer](http://link.springer.com/journal/12282)","snPcode":"12282","submissionUrl":"https://www.editorialmanager.com/brca/default2.aspx","title":"Breast Cancer","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"770aeb9c-bfc4-4152-b93b-d7edb1fe6cde","owner":[],"postedDate":"July 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-29T16:07:21+00:00","versionOfRecord":{"articleIdentity":"rs-7048730","link":"https://doi.org/10.1007/s12282-025-01784-6","journal":{"identity":"breast-cancer","isVorOnly":false,"title":"Breast Cancer"},"publishedOn":"2025-09-25 15:58:19","publishedOnDateReadable":"September 25th, 2025"},"versionCreatedAt":"2025-07-17 11:50:05","video":"","vorDoi":"10.1007/s12282-025-01784-6","vorDoiUrl":"https://doi.org/10.1007/s12282-025-01784-6","workflowStages":[]},"version":"v1","identity":"rs-7048730","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7048730","identity":"rs-7048730","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}