Margin-driven outcomes prevail over resection planes: multivisceral surgery matches total mesorectal excision in locally advanced rectal cancer

Niyaz Shadmanov; Baris Bakir; Suha Goksel; Oktar Asoglu

doi:10.3393/ac.2025.00920.0131

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Original Article Colorectal cancer Margin-driven outcomes prevail over resection planes: multivisceral surgery matches total mesorectal excision in locally advanced rectal cancer: Niyaz Shadmanov¹, Baris Bakir², Suha Goksel³, Oktar Asoglu¹; Annals of Coloproctology 2026;42(2):226-236.
DOI: https://doi.org/10.3393/ac.2025.00920.0131
Published online: April 27, 2026

¹Bogazici Academy for Clinical Sciences, Istanbul, Turkiye

²Department of Radiology, Istanbul Medical Faculty, Istanbul University, Istanbul, Turkiye

³Department of Pathology, Maslak Acıbadem Hospital, Istanbul, Turkiye

Correspondence to: Oktar Asoglu, MD Bogazici Academy for Clinical Sciences, Acısu St, No. 16, Istanbul 34357, Turkiye Email: oktarasoglu@yahoo.com

• Received: July 30, 2025 • Revised: November 4, 2025 • Accepted: November 11, 2025

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Abstract
INTRODUCTION
METHODS
RESULTS
DISCUSSION
ARTICLE INFORMATION
REFERENCES

Abstract

Purpose
This study compared oncologic and perioperative outcomes between patients with locally advanced rectal cancer (LARC) treated with beyond total mesorectal excision (bTME) and those with pathologic stage III disease undergoing TME.
Methods
A retrospective analysis was conducted using prospectively collected data from 580 LARC patients treated with curative-intent surgery over a 23-year period. Patients were categorized as those with clinical T4b tumors who underwent bTME with multivisceral resection (MVR) and those with pathologic stage III tumors treated with TME. Demographic, surgical, pathological, and oncologic outcomes were compared.
Results
Circumferential resection margin (CRM) positivity was similar between the groups (5.3% vs. 3.6%, P=0.467). Postoperative complications occurred more often in the bTME group (28.9% vs. 18.2%, P=0.004), although major complications were comparable (P=0.812). Five-year local recurrence (10.5% vs. 9.3%, P=0.371), distant metastasis (19.7% vs. 21.4%, P=0.140), disease-free survival (64.4% vs. 66.2%, P=0.326), and overall survival (74.8% vs. 75.5%, P=0.464) demonstrated no significant differences. Within the bTME group, 32 patients (42.1%) underwent major MVR and 44 (57.9%) underwent minor MVR. CRM positivity (6.2% vs. 4.5%, P=0.999), local recurrence (12.5% vs. 9.1%, P=0.714), and distant metastasis (25.0% vs. 15.9%, P=0.388) rates were similar. Five-year disease-free survival (61.5% vs. 72.3%, P=0.454) and overall survival (68.5% vs. 74.8%, P=0.609) favored minor MVR, although the differences were not statistically significant.
Conclusion
When negative circumferential margins are achieved, margin-driven bTME resections provide long-term oncologic outcomes comparable to standard TME in high-risk rectal cancer, although they are associated with higher overall complication rates.
Keywords: Rectal neoplasms; Total mesorectal excision; Multivisceral resection; Pelvic exenteration; Margins of excision

INTRODUCTION

Total mesorectal excision (TME) remains the gold standard for the surgical management of rectal cancer, offering excellent local control and long-term oncologic outcomes when performed meticulously [1, 2]. However, TME alone may not provide adequate treatment for patients with clinical T4b tumors that invade adjacent pelvic organs or structures [3, 4]. In such cases, a more extensive approach, beyond TME (bTME), is necessary to secure oncologically sufficient resection margins through en bloc multivisceral resection (MVR) tailored to the tumor’s pattern of spread [5, 6].

Surgical resection with microscopically clear margins (R0 resection) and a negative circumferential resection margin (CRM) has been shown to reduce local recurrence (LR) and distant metastasis (DM), while improving overall survival (OS) [7, 8]. However, an analysis from the American National Cancer Database, which captures approximately 70% of all national cancer cases, reported CRM positivity in more than 30% of resected specimens among 2,239 clinically staged T4 rectal cancer patients who underwent surgery between 2011 and 2016 [9]. These findings underscore the substantial technical challenges involved and the persistently high rates of inadequate margin clearance in this population despite advances in surgical technique.

Although oncologic outcomes following TME for pathologic stage III disease are well established, there remains limited evidence directly comparing long-term outcomes between clinically staged T4b patients treated with bTME and pathologic stage III patients treated with TME. Whether the oncologic outcomes of bTME for locally advanced rectal cancer (LARC) match those achieved with TME in pathologic stage III disease has not yet been clearly determined.

The present study addresses this gap by comparing margin-driven bTME for clinically staged T4b rectal cancer with standard TME for pathologic stage III disease. We hypothesized that when circumferential resection margins are negative, long-term oncologic outcomes would be comparable between the 2 groups.

METHODS

Ethics statement

This retrospective cohort study was approved by the Institutional Review Board of Marmara University Faculty of Medicine (No. 09.2024.1185). Informed consent was waived due to the retrospective design of the study and the use of de-identified data. All study procedures were conducted in accordance with the principles of the Declaration of Helsinki. This study follows the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) reporting guidelines for cohort studies [10].

Study design and patients

Between January 2002 and March 2025, 1,422 patients were diagnosed with rectal cancer. Of these, 1,254 underwent curative-intent radical surgery. A total of 580 patients with LARC who met the inclusion criteria were included in the analysis. Patients were categorized into 2 groups: those with clinical T4b disease based on preoperative high-resolution pelvic magnetic resonance imaging (MRI) who underwent bTME with en bloc MVR (bTME group), and those with pathologically confirmed stage III disease treated with TME (TME group) (Fig. 1). Although clinical and pathological staging systems differ in both timing and methodology, the 2 cohorts represent advanced local disease within the same biological continuum. The key distinction lies in the pattern of local extension, specifically the presence of adjacent organ invasion (cT4b), which determined the need for an extended surgical approach. Thus, the study was not designed to compare tumor stages per se, but rather to evaluate whether achieving a negative CRM could result in comparable oncologic outcomes regardless of the extent of resection. This design reflects real-world surgical decision-making, in which preoperative MRI-based CRM risk and multidisciplinary assessment primarily guide operative planning rather than postoperative pathologic staging.

Data were obtained from a prospectively maintained surgical database. Inclusion criteria were age ≥18 years, histologically confirmed rectal adenocarcinoma, no DM (M0) at diagnosis, absence of synchronous malignancies, and curative-intent radical resection. Exclusion criteria were early-stage tumors (stage I), local or transanal excision, metastatic disease (M1), nonoperative management, and synchronous primary tumors. Performance status and comorbidity profiles were evaluated during multidisciplinary tumor board (MDT) assessment and incorporated into considerations of surgical eligibility.

Study setting

Staging was performed using digital rectal examination, biopsy, colonoscopy, thoracoabdominal computed tomography, and high-resolution pelvic MRI. Clinical T4b staging was confirmed during MDT meetings. All operations adhered to oncologic principles aimed at achieving a clear CRM. The surgical approach (open, laparoscopic, or robotic) was selected according to tumor location, pelvic anatomy, and technical feasibility. TME was performed using sharp mesorectal dissection with autonomic nerve preservation whenever feasible. The bTME procedures involved en bloc resection of adjacent involved structures, including the urinary bladder, uterus, vagina, prostate, seminal vesicles, sacrum, or pelvic sidewall, according to preoperative MRI and/or intraoperative findings. MVR was defined as en bloc removal of adjacent organs or structures to achieve negative margins. MVR was classified as minor when involving resection of a single adjacent organ (e.g., vaginal wall, uterus, or seminal vesicle) and as major when resection included multiple organs or bony structures such as the bladder, prostate, sacrum, or pelvic sidewall. CRM positivity was defined as ≤1 mm between the tumor and the mesorectal fascia, whereas >1 mm was considered negative [7, 8].

Neoadjuvant treatment (NAT) was administered according to tumor location, staging, and institutional protocols. Patients with mid-to-distal rectal tumors, clinically node-positive disease, threatened CRM, or locally advanced features (e.g., extramural vascular invasion–positive, cT4, or N2) were considered for NAT [11]. During the 23-year study period, NAT strategies evolved with institutional policies and updated clinical guidelines. Between 2001 and 2012, most patients received long-course chemoradiotherapy, while short-course chemoradiotherapy was selectively used for elderly or comorbid patients. From 2013 onward, total neoadjuvant therapy was gradually implemented in combination with long- and short-course chemoradiotherapy, based on tumor stage, treatment response, and MDT recommendations.

Tumor response was assessed using restaging MRI and/or endoscopy, with attention to tumor regression, CRM clearance, and nodal status. Treatment decisions were finalized during MDT meetings. Proximal rectal cancers were treated with upfront surgery.

Adjuvant chemotherapy (FOLFOX [fluorouracil, leucovorin, and oxaliplatin], CAPOX [capecitabine and oxaliplatin], or 5-fluorouracil–based regimens) was administered according to postoperative pathologic staging and standard practice at each treatment interval. Patients with stage III or high-risk stage II disease received adjuvant chemotherapy with or without radiotherapy, depending on prior neoadjuvant therapies and intraoperative findings [12]. Follow-up included serum carcinoembryonic antigen and carbohydrate antigen 19-9 monitoring and clinical examination every 3 months for 2 years, followed by every 6 months. Imaging was performed every 6 months for 3 years and then annually. Colonoscopy was conducted at 1 year postoperatively and subsequently according to guideline recommendations.

The primary endpoint was long-term oncologic outcomes, including disease-free survival (DFS) and OS, in patients undergoing bTME and TME. Secondary endpoints included LR, DM, and postoperative complication rates. DFS and OS were defined as the time from surgery to recurrence, death, or last follow-up. LR and DM were identified through radiologic and/or histopathologic confirmation during surveillance and reported as cumulative proportions. Postoperative complications were defined as events occurring within 30 days after surgery and classified using the Clavien-Dindo system.

Median follow-up was 83.9 months (range, 2–225 months) in the bTME group and 99.8 months (range, 2–245 months) in the TME group. All operations were performed by a single experienced colorectal surgeon using standardized techniques, and all pathological and oncologic data were reviewed within the same institutional framework to minimize assessment bias.

Statistical analysis

All statistical analyses were performed using EasyMedStat ver. 2.0 (EasyMedStat). Patients were divided into 2 groups according to the surgical procedure performed: those treated with bTME and those treated with TME. Analyses were conducted to compare demographic characteristics, perioperative data, pathological findings, and oncologic outcomes between the 2 groups.

Categorical variables were expressed as frequencies and percentages and compared using the Pearson chi-square test or Fisher exact test when appropriate. Continuous variables were reported as medians with ranges, and normality was assessed using the Shapiro-Wilk test. Non-normally distributed data were analyzed using the Mann-Whitney U-test.

Oncologic outcomes, including LR, DM, DFS, and OS, were evaluated using the Kaplan-Meier method, and survival differences between groups were assessed using the log-rank test. Patients without recurrence or death were censored at their most recent documented follow-up. All statistical tests were 2-sided, and a P-value of <0.05 was considered statistically significant. Hazard ratios with 95% confidence intervals were not calculated because the study was not designed for multivariable risk modeling.

RESULTS

Patient demographics and baseline clinical features

The median age was 50.7 years (range, 22–73 years) in the bTME group and 56.0 years (range, 20–85 years) in the TME group (P=0.060). Thirty-two patients (42.1%) were male and 44 (57.9%) were female in the bTME group, compared with 290 (57.5%) male patients and 214 (42.5%) female patients in the TME group (P=0.050). The median body mass index was 26.8 kg/m² (range, 18–39 kg/m²) in the bTME group and 25.7 kg/m² (range, 18–39 kg/m²) in the TME group (P=0.343). American Society of Anesthesiologists (ASA) physical status I, II, and III were recorded in 12 (15.8%), 51 (67.1%), and 13 patients (17.1%), respectively, in the bTME group and in 62 (12.3%), 318 (63.1%), and 124 patients (24.6%), respectively, in the TME group (P=0.203).

Tumors in the mid-distal rectum were significantly more common in the bTME group (69.7% vs. 52.2%, P=0.002). Clinical node positivity (cN+) was observed in 55 patients (72.4%) in the bTME group and in 422 (83.7%) in the TME group (P=0.015). NAT was administered to 53 patients (69.7%) in the bTME group and to 288 (57.1%) in the TME group (P=0.073). All patients in the bTME group were clinically staged as T4b, whereas 317 (62.9%) in the TME group had cT4 and 187 (37.1%) had cT3 (P<0.001) (Table 1).

Comparison of operative and pathological characteristics

Abdominoperineal resection and open surgery were performed more frequently in the bTME group than in the TME group (abdominoperineal resection: 18.4% vs. 9.1%, P=0.014; open surgery: 21.1% vs. 12.5%, P=0.042). Laparoscopic and robotic approaches were used in 48 (63.2%) and 12 (15.8%) bTME procedures and in 374 (74.2%) and 67 (13.3%) TME procedures, respectively. Conversion to open surgery occurred more often in the bTME group (11.8% vs. 2.8%, P<0.001). The median operative time was longer in the bTME group (154.2 minutes; range, 80–260 minutes) than in the TME group (134.7 minutes; range, 60–390 minutes), although this difference was not statistically significant (P=0.064).

Among patients who received NAT, ypT category distributions in the bTME versus TME groups were as follows: ypT0, 1 (1.3%) vs. 0; ypT2, 3 (3.9%) vs. 38 (7.5%); ypT3, 21 (27.6%) vs. 215 (42.7%); ypT4a, 6 (7.9%) vs. 35 (6.9%); and ypT4b, 22 (28.9%) vs. 0 (P=0.245). After upfront surgery, pT3 occurred in 8 (10.5%) vs. 138 (27.4%), pT4a in 3 (3.9%) vs. 74 (14.7%), and pT4b in 12 (15.8%) vs. 0 patients, respectively (P=0.040).

In the subgroup that received NAT, 25 patients (32.9%) in the bTME group were ypN– and 28 (36.8%) were ypN+. Among those who underwent upfront surgery, 8 patients (10.5%) in the bTME group were pN– and 15 (19.7%) were pN+. All patients in the TME group were y(p)N+ by study design.

CRM positivity was observed in 4 patients (5.3%) in the bTME group and in 18 (3.6%) in the TME group, with no significant difference (P=0.467). Median tumor size was significantly larger in the bTME group at 49.6 mm (range, 15–110 mm) compared with 43.4 mm (range, 8–120 mm) in the TME group (P=0.004) (Table 2).

Clinical and oncological outcomes according to the extent of MVR

Among the 76 patients in the bTME group, 32 (42.1%) underwent major MVR and 44 (57.9%) underwent minor MVR. In the major MVR group, 20 (62.5%) were female and 12 (37.5%) were male, while in the minor MVR group, 24 (54.5%) were female and 20 (45.5%) were male. NAT was administered to 25 patients (78.1%) in the major MVR group and in 28 patients (63.6%) in the minor MVR group.

The anatomical distribution of major MVR included anterior pelvic exenteration (PE) in 68.8% (7 female and 15 male patients), total PE in 25.0% (5 male and 3 female patients), and posterior PE in 6.2% (both female patients).

Among patients who received NAT, pathological staging in the major MVR group showed ypT0–T3 in 10 (31.3%), ypT4a in 2 (6.2%), and ypT4b in 13 (40.6%), and 14 (31.8%), 4 (9.1%), and 10 (22.7%), respectively, in the minor MVR group (P=0.458 for ypT0–T3). Among patients without NAT, the major MVR group demonstrated pT3 in 2 (6.2%), pT4a in 1 (3.1%), and pT4b in 4 (12.5%), while the minor MVR group had 4 (9.1%), 5 (11.4%), and 7 (15.9%), respectively (P=0.667 for pT3).

According to the Clavien-Dindo classification, minor complications (grade I–II) occurred significantly more often after major MVR than after minor MVR (31.2% vs. 11.4%, P=0.039). Major complications (grade III–IV) were also more frequent after major MVR, although this difference did not reach statistical significance (15.6% vs. 4.5%, P=0.122).

Median follow-up was 81.2 months (range, 2–225 months) in the major MVR group and 89.2 months (range, 2–245 months) in the minor MVR group (P=0.128). LR occurred in 4 patients (12.5%) in the major MVR group and 4 patients (9.1%) in the minor MVR group (P=0.714). DM was observed in 8 (25.0%) and 7 (15.9%), respectively (P=0.388). The 5-year DFS rate was 61.5% in the major MVR group and 72.3% in the minor MVR group (P=0.454). OS rates were 68.5% and 74.8%, respectively (P=0.609) (Table 3).

Among the 8 patients who underwent total PE, dead space management included myocutaneous flap reconstruction in 3, omentoplasty in 3, and omentoplasty combined with breast implant insertion in 2.

Extent of resection in the bTME group

Bladder resection was performed in 9 patients (7 male and 2 female patients). Five patients did not receive NAT, while 4 did. Pathological examination revealed pT3 tumors in 3 patients, pT4b in 2, ypT4a in 1, and ypT4b in 3 patients. None had a positive CRM, and 1 patient developed LR at 14 months. Partial cystectomy was performed in 4 patients (2 female and 1 male patients). In 3 male patients, bladder resection was combined with additional pelvic organ resections, including the seminal vesicles in 1 and the prostate in 2.

Sacral resection was carried out in 3 male patients: 1 underwent coccygectomy, and 2 underwent S4-level sacral resection. Pathological analysis demonstrated ypT4b tumors in 2 patients and pT4a in 1. One patient developed a presacral LR at 8 months.

Hysterectomy was performed in 18 female patients, including 7 who did not receive NAT and 11 who did. Pathology identified pT3 in 2, pT4b in 5, ypT3 in 7, and ypT4b in 4 patients. LR occurred in 2 patients, at 14 and 16 months. In 1 patient, hysterectomy was performed together with vaginal and ureteral resection.

Vaginal resection was performed in 19 female patients; only 1 had not received NAT. Pathological staging revealed pT3 in 1 patient, ypT3 in 7, ypT4a in 2, ypT4b in 8, and ypT2 in 1 patient. One patient developed LR at 6 months. In 1 case, vaginal resection was performed in combination with hysterectomy.

Prostatectomy was undertaken in 8 male patients, 3 of whom had not received NAT. Pathology showed pT3 in 1 patient, ypT3 in 3, and ypT4b in 4 patients. No CRM positivity or LR was observed.

Seminal vesicle resection was performed in 4 male patients, 2 without NAT. Pathology demonstrated pT3 in 1, pT4b in 1, and ypT4b in 2 patients. No LR occurred.

Small bowel resection was performed in 7 patients, 2 of whom received NAT. Pathological staging showed pT4b in 3, pT4a in 1, pT3 in 1, ypT4a in 1, and ypT3 in 1 patient.

Additional resections of pelvic side structures were performed in 12 patients. Left ureteral resection was conducted in 2 patients who had received NAT, with pathology showing ypT3 and ypT4b disease. In 1 case, this resection was combined with hysterectomy. Ovarian resection was performed in 3 female patients, all of whom received NAT; pathology revealed ypT4b in 2 patients and pT0 in 1. Pelvic peritoneum resection was performed in 6 patients, including 2 who did not receive NAT. Pathology showed pT3 in 1, pT4b in 1, ypT4a in 1, ypT4b in 2, ypT2 in 1, and ypT3 in 1 patient.

Postoperative complications

The overall postoperative complication rate was significantly higher in the bTME group compared with the TME group (28.9% vs. 18.2%, P=0.004). Reoperations were also more frequent in the bTME group (3.9% vs. 1.2%, P=0.024).

Anastomotic leakage occurred in 6 patients (7.9%) in the bTME group and 38 patients (7.5%) in the TME group (P=0.738). Pelvic collections or pelvic fistulas were reported in 4 patients (5.3%) in the bTME group and in 18 patients (3.6%) in the TME group (P=0.127). Mechanical small bowel obstruction occurred more often in the bTME group (3.9% vs. 2.8%, P<0.001). Urinary retention was noted in 3 patients (3.9%) in the bTME group and 2 (0.4%) in the TME group (P<0.001). Surgical site infections were also significantly more common in the bTME group (7.9% vs. 4.0%, P<0.001).

Clavien-Dindo grade I–II complications occurred in 15 of 22 patients (68.2%) in the bTME group and in 56 patients (60.9%) in the TME group (P=0.718). The rates of grade III–IV complications were comparable between the groups (31.8% vs. 39.1%, P=0.812) (Table 4).

Oncological outcomes

The median follow-up was 83.9 months (range, 2–225 months) in the bTME group and 99.8 months (range, 2–245 months) in the TME group (P=0.128). The 5-year oncologic outcomes demonstrated no significant differences between the 2 groups Table 5. The 5-year LR rate was 10.5% in the bTME group and 9.3% in the TME group (P=0.371). The 5-year DM rate was 19.7% in the bTME group and 21.4% in the TME group (P=0.140). The 5-year DFS was 64.4% in the bTME group and 66.2% in the TME group (P=0.326). Similarly, the 5-year OS rates were 74.8% in the bTME group and 75.5% in the TME group (P=0.464). Kaplan-Meier survival curves for LR, DM, DFS, and OS are shown in Figs. 2 and 3.

DISCUSSION

The aim of this study was to evaluate whether patients with LARC who were clinically staged as cT4b on preoperative MRI and treated with bTME could achieve long-term oncologic outcomes comparable to those of patients with pathologic stage III disease treated with TME.

The reported percentage of cases needing exenterative surgery in LARC ranges from 6% to 10% in the literature [13]. In the present series, the MVR rate was 13.1% (76 of 580), which aligns with these observations.

CRM positivity rates following MVR for clinically staged cT4 rectal cancer have been reported to range between 14% and 21% [14, 15]. The PelvEx Collaborative documented a rate of 21.2%, while a nationwide population-based Dutch study reported CRM positivity rates of 21% in patients undergoing MVR and 14% in those treated with TME [16, 17]. Likewise, a large Swedish national series found rates of 15.4% in patients undergoing bTME and 8.6% in those undergoing TME [18].

Despite the presence of adjacent organ involvement in the bTME group, the CRM positivity rate in this series was 5.3% for bTME and 3.6% for TME, indicating comparable outcomes (P=0.467). This favorable result likely reflects our strict surgical policy of performing MVR in all cases with suspected adjacent organ involvement (cT4b) based on initial MRI assessment.

Therefore, the low CRM positivity observed in this study can be interpreted as a positive outcome of bTME. In this cohort, pT4b disease was confirmed in only 42.1% of patients who received NAT and 52.2% of those who did not. These findings indicate that in approximately half of the cases, extended resection was performed without histopathologic confirmation of adjacent organ invasion.

One explanation may be the limitations of preoperative MRI in accurately defining the true depth of tumor invasion. In patients who received NAT, treatment-induced fibrosis and desmoplastic reaction may obscure tumor boundaries on post-treatment MRI, increasing the likelihood of overstaging regardless of magnetic resonance tumor regression grade interpretation. Similarly, in patients who did not receive NAT, MRI-based clinical staging may overestimate the extent of invasion and result in inaccurate assessment. In a meta-analysis, Wei et al. [19] reported that only 70% to 80% of patients staged as cT4 on MRI were ultimately confirmed to have pT4 disease on final histopathology.

In our series, among the 76 patients who underwent bTME for clinically suspected cT4b disease, only 44.7% were confirmed as pT4b at final histopathology (28.9% ypT4b after neoadjuvant therapy and 15.8% pT4b after upfront surgery). This finding further illustrates the diagnostic limitations of MRI, as fibrosis, desmoplastic reaction, and inflammatory adhesions may mimic true tumor extension. Consistent with these observations, previous studies have reported MRI accuracy rates between 60% and 75% for evaluating adjacent organ involvement in LARC, influenced by image quality and radiologist expertise [19, 20]. These limitations can contribute to overstaging and raise concern about the potential for overtreatment. However, in this study, surgical decision-making did not rely solely on MRI findings but rather on the risk of CRM involvement, the presence of tumor fixation, and the feasibility of achieving a negative margin. All bTME procedures were planned within a multidisciplinary tumor board. Consequently, even in patients without pT4b invasion, the extended resections performed should be interpreted as margin-driven and safety-oriented rather than unnecessary overtreatment.

Sugimoto et al. [21] demonstrated that CRM positivity is one of the strongest independent predictors of both 5-year LR-free survival (49.3%) and 5-year recurrence-free survival (15.7%). In the PelvEx Collaborative study, patients undergoing MVR had a 5-year LR rate of 12.5% and an OS rate of 68% [16]. In the Dutch study, the bTME group showed an LR rate of 14.6% and a 5-year DFS of 56.2%, whereas the TME group had an LR rate of 8.4% and a DFS of 66.6% [17]. In the Swedish study, although LR and DFS for the entire cohort were not reported, the 5-year relative survival for patients undergoing R0 resection was 78% after bTME compared with 87% after TME, with no statistically significant difference [18].

In the present study, the CRM positivity rate in the bTME group was comparable to that of the TME group, which included patients with pathologic stage III disease without adjacent organ invasion. Consistent with this, the bTME group exhibited an LR rate of 10.5%, a 5-year DFS of 64.4%, and a 5-year OS of 74.8%, outcomes that closely matched those of the TME group (9.3%, 66.2%, and 75.5%, respectively).

The complication rates have been shown to be higher in patients undergoing MVR. For instance, in the study by Arndt et al. [22], the complication rate was reported as 46.3%, which was significantly higher than that observed in the TME group (37.2% vs. 46.3%; P<0.001). In the present series, the overall complication rate in the bTME group was 28.9%, significantly higher than the 18.2% observed in the TME group (P=0.004). However, when evaluated according to the Clavien-Dindo classification, no significant difference was found between the groups with respect to major complications (grade III–IV), with rates of 31.8% in the bTME group and 28.6% in the TME group (P=0.812). This finding is consistent with the Dutch study, which reported grade III–IV complication rates ranging from 10% to 22% [17]. Taken together, these results suggest that although bTME increases overall complication rates, its safety profile regarding major complications is comparable to that of TME [5].

Although the overall morbidity was higher in the bTME group, this difference likely reflects the increased surgical complexity and wider extent of resection required for locally advanced disease rather than inferior technique or oncologic compromise. Importantly, despite the higher complication rate, long-term oncologic outcomes, including LR, DM, DFS, and OS, remained comparable between the groups. This finding suggests that a margin-oriented bTME approach ensures oncologic safety at the cost of acceptable morbidity, an inherent trade-off in curative surgery for LARC.

In the present study, 32 patients (42.1%) in the bTME group underwent PE. This subgroup included patients with the most anatomically extensive local invasion and with the highest technical and complication-related risks. In the PE group, CRM positivity was 6.2%, LR was 12.5%, and the 5-year OS was 68.5%. These outcomes are consistent with those reported in large single-center series, which have demonstrated 5-year OS rates ranging from 30% to 68% following PE [23–26].

In all 8 cases of total PE in our series, pelvic dead space was meticulously managed using specialized reconstructive techniques to reduce the risk of postoperative complications. Myocutaneous flap reconstruction was performed in 3 patients, omentoplasty in 3, and omentoplasty combined with breast implant insertion in 2. These strategies were selected based on patient anatomy, the extent of resection, and surgeon preference, with the goal of minimizing dead space and preventing complications.

As a result of these approaches, no major perineal infections occurred, and no significant wound-related complications were observed. These outcomes are noteworthy given the well-documented, high perineal wound complication rates, reported to range between 20% and 40%, following total PE [4, 27].

These findings indicate that in patients clinically assessed as cT4b and treated with bTME, appropriate surgical strategy and meticulous technique can achieve low CRM positivity and acceptable recurrence rates, ultimately yielding long-term oncologic outcomes comparable to those obtained in patients with pathologic stage III disease treated with TME.

This study has inherent limitations related to its retrospective design and long study period. Although all procedures were performed by a single experienced surgeon, the unequal subgroup sizes, temporal variations, and absence of multivariable modeling may have introduced selection bias and limited the generalizability of the findings.

While the bTME and TME groups were defined by clinical (cT4b) and pathological (stage III) criteria, respectively, both groups represent the same overall disease spectrum. The difference lies solely in the degree of local invasion and the corresponding extent of surgery required to achieve a negative CRM. The comparison was intended to test our hypothesis that margin negativity, rather than the extent of surgical resection, is the key determinant of long-term oncologic outcomes in LARC.

Conclusions

In clinically staged T4b rectal cancer, surgical strategy should be guided primarily by high-resolution preoperative MRI, regardless of whether neoadjuvant therapy is administered. The principal goal is to achieve an R0 resection with a negative CRM, which often necessitates tailored MVR. Our findings indicate that when performed with meticulous preoperative planning and MRI-based assessment, bTME can provide long-term oncologic outcomes that approximate those of standard TME for pathologic stage III disease. Although associated with higher perioperative morbidity, bTME remains a valid and effective curative approach for appropriately selected patients with LARC.

ARTICLE INFORMATION

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

None.

Acknowledgments

The authors thank all colleagues who contributed to the clinical management of patients included in this study.

Author contributions

Conceptualization: OA; Formal analysis: all authors; Investigation: all authors; Methodology: NS, OA; Supervision: OA; Writing–original draft: NS, OA; Writing–review & editing: all authors. All authors read and approved the final manuscript.

Fig. 1.

Flowchart of the study. NOM, nonoperative management; TME, total mesorectal excision; pStage, pathologic stage; MVR, multivisceral resection; bTME, beyond total mesorectal excision.

Fig. 2.

Kaplan-Meier curves for (A) local recurrence (LR)-free survival, (B) distant metastasis (DM)-free survival, (C) disease-free survival, and (D) overall survival in patients undergoing beyond total mesorectal excision (bTME) versus TME.

Fig. 3.

Kaplan-Meier curves for (A) local recurrence (LR)-free survival, (B) distant metastasis (DM)-free survival, (C) disease-free survival, and (D) overall survival in patients undergoing major multivisceral resection (MVR) versus minor MVR.

Table 1.

Patient demographics and baseline clinical features (n=580)

Characteristic	bTME group (n=76)	TME group (n=504)	P-value
Age (yr)	50.7 (22–73)	56.0 (20–85)	0.060
Sex			0.050
Male	32 (42.1)	290 (57.5)
Female	44 (57.9)	214 (42.5)
ASA physical status			0.203
I	12 (15.8)	62 (12.3)
II	51 (67.1)	318 (63.1)
III	13 (17.1)	124 (24.6)
Body mass index (kg/m²)	26.8 (18–39)	25.7 (18–39)	0.343
Localization			0.002
Mid-distal	53 (69.7)	263 (52.2)
Proximal	23 (30.3)	241 (47.8)
Clinical classification
cT category			<0.001
cT3	0 (0)	187 (37.1)
cT4	76 (100)	317 (62.9)
cN category			0.015
cN+	55 (72.4)	422 (83.7)
cN–	21 (27.6)	82 (16.3)
Neoadjuvant treatment	53 (69.7)	288 (57.1)	0.073

Values are presented as median (range) or number (%). Comparisons were performed using the Pearson chi-square test for categorical variables and the Mann-Whitney U-test for continuous variables.

bTME, beyond total mesorectal excision; TME, total mesorectal excision; ASA, American Society of Anesthesiologists.

Table 2.

Comparison of operative and pathological characteristics (n=580)

Characteristic	bTME group (n=76)	TME group (n=504)	P-value
TME procedure			0.014
Abdominoperineal resection	14 (18.4)	46 (9.1)
Sphincter-preserving	62 (81.6)	458 (90.9)
Surgical technique			0.042
Open	16 (21.1)	63 (12.5)
Laparoscopic	48 (63.2)	374 (74.2)
Robotic	12 (15.8)	67 (13.3)
Conversion	9 (11.8)	14 (2.8)	<0.001
Operative time (min)	154.2 (80–260)	134.7 (60–390)	0.064
Pathological classification
yT category			0.245
ypT0	1 (1.3)	0 (0)
ypT2	3 (3.9)	38 (7.5)
ypT3	21 (27.6)	215 (42.7)
ypT4a	6 (7.9)	35 (6.9)
ypT4b	22 (28.9)	0 (0)
yN category			<0.001
ypN–	25 (32.9)	0 (0)
ypN+	28 (36.8)	288 (57.1)
pT category			0.040
pT2	0 (0)	4 (0.8)
pT3	8 (10.5)	138 (27.4)
pT4a	3 (3.9)	74 (14.7)
pT4b	12 (15.8)	0 (0)
pN category			<0.001
pN–	8 (10.5)	0 (0)
pN+	15 (19.7)	216 (42.9)
Tumor size (mm)	49.6 (15–110)	43.4 (8–120)	0.004
CRM positivity	4 (5.3)	18 (3.6)	0.467

Values are presented as number (%) or median (range). Percentages may not total 100 due to rounding. Appropriate statistical tests, including the Pearson chi-square test, Fisher exact test, or Mann-Whitney U-test, were used as applicable.

bTME, beyond total mesorectal excision; TME, total mesorectal excision; CRM, circumferential resection margin.

Table 3.

Clinical and oncological outcomes according to the extent of MVR (n=76)

Characteristic	Major MVR (n=32)	Minor MVR (n=44)	P-value
Age (yr)	53.6 (28–71)	54.2 (22–73)	0.189
Sex			0.488
Male	12 (37.5)	20 (45.5)
Female	20 (62.5)	24 (54.5)
ASA physical status			0.464
I	6 (18.8)	6 (13.6)
II	19 (59.4)	32 (72.7)
III	7 (21.9)	6 (13.6)
Body mass index (kg/m²)	27.1 (18–39)	26.5 (22–38)	0.264
Localization			0.086
Mid-distal	18 (56.3)	33 (75.0)
Proximal	14 (43.8)	11 (25.0)
Neoadjuvant treatment	25 (78.1)	28 (63.6)	0.213
Pathological classification
ypT category			0.562
ypT0–T3	9 (28.1)	16 (36.4)
ypT4a	2 (6.2)	4 (9.1)
ypT4b	12 (37.5)	10 (22.7)
ypN category			0.391
ypN+	13 (40.6)	15 (34.1)
ypN–	12 (37.5)	13 (29.5)
pT category			0.307
pT3	2 (6.2)	4 (9.1)
pT4a	1 (3.1)	5 (11.4)
pT4b	4 (12.5)	7 (15.9)
pN category			0.153
pN+	3 (9.4)	12 (27.3)
pN–	5 (15.6)	3 (6.8)
Clavien-Dindo classification
I–II (minor complication)	10 (31.2)	5 (11.4)	0.039
III–IV (major complication)	5 (15.6)	2 (4.5)	0.122
CRM positivity	2 (6.2)	2 (4.5)	0.999
Local recurrence	4 (12.5)	4 (9.1)	0.714
Distant metastasis	8 (25.0)	7 (15.9)	0.388
5-year DFS (%)	61.5	72.3	0.454
5-year OS (%)	68.5	74.8	0.609

Values are presented as median (range) or number (%), unless otherwise indicated. Percentages may not total 100 due to rounding. Appropriate statistical tests, including the Pearson chi-square test, Fisher exact test, or Mann-Whitney U-test, were used as applicable.

MVR, multivisceral resection; ASA, American Society of Anesthesiologists; CRM, circumferential resection margin; DFS, disease free survival; OS, overall survival.

Table 4.

Postoperative complications (n=580)

Outcome	bTME group (n=76)	TME group (n=504)	P-value
Reoperation	3 (3.9)	6 (1.2)	0.024
Complication	22 (28.9)	92 (18.2)	0.004
Anastomotic leak	6 (7.9)	38 (7.5)	0.738
Pelvic collection/fistula	4 (5.3)	18 (3.6)	0.127
Mechanical small bowel obstruction	3 (3.9)	14 (2.8)	<0.001
Urinary retention	3 (3.9)	2 (0.4)	<0.001
Surgical site infection	6 (7.9)	20 (4.0)	<0.001
Clavien-Dindo classification
I–II (minor complication)	15 (68.2)	56 (60.9)	0.718
III–IV (major complication)	7 (31.8)	36 (39.1)	0.636

Values are presented as number (%). Statistical comparisons were made using the Pearson chi-square or Fisher exact test, as appropriate.

bTME, beyond total mesorectal excision; TME, total mesorectal excision.

Table 5.

The 5-year oncological outcomes (n=580)

Outcome	bTME group (n=76)	TME group (n=504)	P-value
Local recurrence	8 (10.5)	47 (9.3)	0.371
Distant metastasis	15 (19.7)	108 (21.4)	0.140
Overall survival (%)	74.8	75.5	0.464
Disease-free survival (%)	64.4	66.2	0.326
Follow-up (mo)	83.9 (2–225)	99.8 (2–245)	0.128

Values are presented as number (%) or median (range), unless otherwise indicated. Statistical comparisons were performed using the Pearson chi-square test for categorical variables and the Mann-Whitney U-test for continuous variables. Statistical comparisons were made using the Pearson chi-square or Fisher exact test, as appropriate.

bTME, beyond total mesorectal excision; TME, total mesorectal excision.

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Margin-driven outcomes prevail over resection planes: multivisceral surgery matches total mesorectal excision in locally advanced rectal cancer

Ann Coloproctol. 2026;42(2):226-236. Published online April 27, 2026

DOI: https://doi.org/10.3393/ac.2025.00920.0131

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Advances in surgery for locally advanced rectal cancer

Margin-driven outcomes prevail over resection planes: multivisceral surgery matches total mesorectal excision in locally advanced rectal cancer

Fig. 1. Flowchart of the study. NOM, nonoperative management; TME, total mesorectal excision; pStage, pathologic stage; MVR, multivisceral resection; bTME, beyond total mesorectal excision.

Fig. 2. Kaplan-Meier curves for (A) local recurrence (LR)-free survival, (B) distant metastasis (DM)-free survival, (C) disease-free survival, and (D) overall survival in patients undergoing beyond total mesorectal excision (bTME) versus TME.

Fig. 3. Kaplan-Meier curves for (A) local recurrence (LR)-free survival, (B) distant metastasis (DM)-free survival, (C) disease-free survival, and (D) overall survival in patients undergoing major multivisceral resection (MVR) versus minor MVR.

Fig. 1.

Fig. 2.

Fig. 3.

Margin-driven outcomes prevail over resection planes: multivisceral surgery matches total mesorectal excision in locally advanced rectal cancer

Characteristic	bTME group (n=76)	TME group (n=504)	P-value
Age (yr)	50.7 (22–73)	56.0 (20–85)	0.060
Sex			0.050
Male	32 (42.1)	290 (57.5)
Female	44 (57.9)	214 (42.5)
ASA physical status			0.203
I	12 (15.8)	62 (12.3)
II	51 (67.1)	318 (63.1)
III	13 (17.1)	124 (24.6)
Body mass index (kg/m²)	26.8 (18–39)	25.7 (18–39)	0.343
Localization			0.002
Mid-distal	53 (69.7)	263 (52.2)
Proximal	23 (30.3)	241 (47.8)
Clinical classification
cT category			<0.001
cT3	0 (0)	187 (37.1)
cT4	76 (100)	317 (62.9)
cN category			0.015
cN+	55 (72.4)	422 (83.7)
cN–	21 (27.6)	82 (16.3)
Neoadjuvant treatment	53 (69.7)	288 (57.1)	0.073

Characteristic	bTME group (n=76)	TME group (n=504)	P-value
TME procedure			0.014
Abdominoperineal resection	14 (18.4)	46 (9.1)
Sphincter-preserving	62 (81.6)	458 (90.9)
Surgical technique			0.042
Open	16 (21.1)	63 (12.5)
Laparoscopic	48 (63.2)	374 (74.2)
Robotic	12 (15.8)	67 (13.3)
Conversion	9 (11.8)	14 (2.8)	<0.001
Operative time (min)	154.2 (80–260)	134.7 (60–390)	0.064
Pathological classification
yT category			0.245
ypT0	1 (1.3)	0 (0)
ypT2	3 (3.9)	38 (7.5)
ypT3	21 (27.6)	215 (42.7)
ypT4a	6 (7.9)	35 (6.9)
ypT4b	22 (28.9)	0 (0)
yN category			<0.001
ypN–	25 (32.9)	0 (0)
ypN+	28 (36.8)	288 (57.1)
pT category			0.040
pT2	0 (0)	4 (0.8)
pT3	8 (10.5)	138 (27.4)
pT4a	3 (3.9)	74 (14.7)
pT4b	12 (15.8)	0 (0)
pN category			<0.001
pN–	8 (10.5)	0 (0)
pN+	15 (19.7)	216 (42.9)
Tumor size (mm)	49.6 (15–110)	43.4 (8–120)	0.004
CRM positivity	4 (5.3)	18 (3.6)	0.467

Characteristic	Major MVR (n=32)	Minor MVR (n=44)	P-value
Age (yr)	53.6 (28–71)	54.2 (22–73)	0.189
Sex			0.488
Male	12 (37.5)	20 (45.5)
Female	20 (62.5)	24 (54.5)
ASA physical status			0.464
I	6 (18.8)	6 (13.6)
II	19 (59.4)	32 (72.7)
III	7 (21.9)	6 (13.6)
Body mass index (kg/m²)	27.1 (18–39)	26.5 (22–38)	0.264
Localization			0.086
Mid-distal	18 (56.3)	33 (75.0)
Proximal	14 (43.8)	11 (25.0)
Neoadjuvant treatment	25 (78.1)	28 (63.6)	0.213
Pathological classification
ypT category			0.562
ypT0–T3	9 (28.1)	16 (36.4)
ypT4a	2 (6.2)	4 (9.1)
ypT4b	12 (37.5)	10 (22.7)
ypN category			0.391
ypN+	13 (40.6)	15 (34.1)
ypN–	12 (37.5)	13 (29.5)
pT category			0.307
pT3	2 (6.2)	4 (9.1)
pT4a	1 (3.1)	5 (11.4)
pT4b	4 (12.5)	7 (15.9)
pN category			0.153
pN+	3 (9.4)	12 (27.3)
pN–	5 (15.6)	3 (6.8)
Clavien-Dindo classification
I–II (minor complication)	10 (31.2)	5 (11.4)	0.039
III–IV (major complication)	5 (15.6)	2 (4.5)	0.122
CRM positivity	2 (6.2)	2 (4.5)	0.999
Local recurrence	4 (12.5)	4 (9.1)	0.714
Distant metastasis	8 (25.0)	7 (15.9)	0.388
5-year DFS (%)	61.5	72.3	0.454
5-year OS (%)	68.5	74.8	0.609

Outcome	bTME group (n=76)	TME group (n=504)	P-value
Reoperation	3 (3.9)	6 (1.2)	0.024
Complication	22 (28.9)	92 (18.2)	0.004
Anastomotic leak	6 (7.9)	38 (7.5)	0.738
Pelvic collection/fistula	4 (5.3)	18 (3.6)	0.127
Mechanical small bowel obstruction	3 (3.9)	14 (2.8)	<0.001
Urinary retention	3 (3.9)	2 (0.4)	<0.001
Surgical site infection	6 (7.9)	20 (4.0)	<0.001
Clavien-Dindo classification
I–II (minor complication)	15 (68.2)	56 (60.9)	0.718
III–IV (major complication)	7 (31.8)	36 (39.1)	0.636

Outcome	bTME group (n=76)	TME group (n=504)	P-value
Local recurrence	8 (10.5)	47 (9.3)	0.371
Distant metastasis	15 (19.7)	108 (21.4)	0.140
Overall survival (%)	74.8	75.5	0.464
Disease-free survival (%)	64.4	66.2	0.326
Follow-up (mo)	83.9 (2–225)	99.8 (2–245)	0.128

Table 1. Patient demographics and baseline clinical features (n=580)

Values are presented as median (range) or number (%). Comparisons were performed using the Pearson chi-square test for categorical variables and the Mann-Whitney U-test for continuous variables.

bTME, beyond total mesorectal excision; TME, total mesorectal excision; ASA, American Society of Anesthesiologists.

Table 2. Comparison of operative and pathological characteristics (n=580)

bTME, beyond total mesorectal excision; TME, total mesorectal excision; CRM, circumferential resection margin.

Table 3. Clinical and oncological outcomes according to the extent of MVR (n=76)

MVR, multivisceral resection; ASA, American Society of Anesthesiologists; CRM, circumferential resection margin; DFS, disease free survival; OS, overall survival.

Table 4. Postoperative complications (n=580)

Values are presented as number (%). Statistical comparisons were made using the Pearson chi-square or Fisher exact test, as appropriate.