Meta-analysis of surgical quality-related factors associated with local recurrence rate after rectal cancer surgery

Abstract

BACKGROUND

Despite treatment advances, rectal cancer continues to pose a considerable global health burden, and local recurrence remains an important driver of long-term outcomes. Despite the evolution of surgical technique and multimodal therapy, local recurrence rates (LRRs) remain heterogeneous across institutions, thought to be related to differences in surgical quality. Local recurrence risk has been associated with several surgical quality indicators such as circumferential resection margin (CRM) involvement, total mesorectal excision (TME) quality and surgeon experience. However, the exact relative contribution of each factor is not fully defined.

AIM

To assess factors associated with a change in LRR after rectal cancer surgery and to quantify their contribution to oncological outcome by means of systematic evaluation.

METHODS

MEDLINE/PubMed, EMBASE, and the Cochrane Library were searched thoroughly through 30 November, 2025. In addition, studies correlating local recurrence with surgical quality factors (CRM status, TME quality grade, surgeon volume, hospital volume and operative time) in rectal cancer patients were included. Main outcome measures were LRR at 3 years and 5 years, and disease-free survival (DFS) and overall survival (OS). Quality assessment was done using the Newcastle-Ottawa Scale for observational studies and Cochrane Risk of Bias tool for randomized trials. Heterogeneity was assessed using I² statistic and random-effects models were used with meta-analysis for treatment comparisons.

RESULTS

Meta-analysis included 10 studies with 11525 patients. Positive CRM was the most significant predictor of local recurrence [odds ratio (OR) = 4.28, 95% confidence interval (95%CI): 3.45-5.31, P < 0.001], with a corresponding LRR at 5 years of 18.7% in positive vs 14 cases (4.2%) in CRM-negative cases. If report shows incomplete TME (mesorectal plane) yes OR = 3.16 (95%CI: 2.48-4.03, P < 0.001) compared with complete TME no compared to low-volume surgeons (< 10 cases/year), high-volume surgeons (> 20 cases/year) had lower LRR (OR = 0.58, 95%CI: 0.45-0.75, P < 0.001). The predictors of LRR included hospital volume > 50 cases/year (OR = 0.66, 95%CI: 0.51-0.86, P = 0.002). Long operative time (> 240 minutes) was associated with LRR rates (OR = 1.52, 95%CI: 1.18-1.96, P = 0.001). TME and CRM positivity were independent risk factors for worse DFS [hazard ratio (HR) = 2.84, 95%CI: 2.31-3.49 for incomplete TME and HR = 2.12, 95%CI: 1.74-2.58 for positive CRM] and OS (HR = 2.56, 95%CI: 2.08-3.15; HR = 1.89, P < 0.001).

CONCLUSION

The behaviour of LRRs after rectal cancer surgery is highly influenced by surgical quality. Modifiable factors include CRM involvement and incompleteness of TME. The results corroborate the rationale for centralization of rectal cancer surgery to high-volume centers and experienced surgeons, coupled with comprehensive quality assurance programs focused on proper TME technique and negative margins as a means to reduce LRRs and improve survival. Nonetheless, the current meta-analysis shows correlations instead of directly testing centralization policy effectiveness.

Key Words: Rectal cancer; Local recurrence; Circumferential resection margin; Total mesorectal excision; Surgical quality; Surgeon volume; Hospital volume; Meta-analysis

Core Tip: Positive circumferential resection margin identifies patients at 4.3-fold increase risk of local recurrence emergence as strongest predictor; whereas incomplete total mesorectal excision confers 3.2-fold increased risk. Recurrence rates are significantly lower at high-volume surgeons and centers. This highlights the need for surgical quality assurance programs, specialization in rectal cancer surgery and centralization of treatment to further improve oncological results. While the meta-analysis by does not explicitly test a centralization policy, its findings align with what one would expect based on the rationale for quality-based referral patterns and training initiatives.

INTRODUCTION

Around 30%-35% of colorectal cancers are rectal cancer, it accounts for about 340000 new cases per year worldwide[1]. Introduction Local recurrence after curative resection constitutes an important clinical challenge, with rates of 5%-15% and adverse effects on both quality of life and survival[2,3], despite major advancements in surgical techniques, neoadjuvant therapy and multidisciplinary care. Lasting impacts include worse recurrence free survival when it comes to local, but not distant metastases (which are rarely salvageable and invariably fatal), as well as severe pelvic symptoms, often presenting with pain, bleeding or reduced functionality.

Heald introduced total mesorectal excision (TME) in the 1980s, significantly changing rectal cancer surgery practice[4], with local recurrence rates (LRRs) previously ranging from 20% to 40% dropping to less than 10% in specialized centers[5,6]. TME is the removal of the mesorectum with its fascial envelope intact, using sharp dissection in accordance with embryological planes to ensure maximal oncological clearance whilst preserving pelvic autonomic nerves. The quality of TME, evaluated by macroscopic assessment of the mesorectal excised specimen has previously been shown to correlate with oncological outcome[7-10]. LRRs of 4%-8% can be achieved with complete TME using an intact mesorectal envelope, whereas incomplete TME with defects at the muscularis propria have been associated with LRR of 15%-25%[10-12]. With advances in minimally invasive program which rely on technique depending surgical approach (i.e., laparoscopic, robotic) for cancer surgery, recent multicenter studies have confirmed that TME quality still holds true as an important factor governing local recurrence[3-7]. Contemporary guidelines and multicenter studies have further emphasized standardized TME assessment, surgical quality control, and margin evaluation as key components of rectal cancer management[13-17].

One of the most significant prognostic factors in rectal cancer is circumferential resection margin (CRM), which is defined as the minimum distance from a radial resection plane to the closest tumor or lymph node[18-20]. As described, a positive CRM (traditionally defined as tumor within 1 mm of the resection margin) indicates incomplete excision and is strongly correlated with local recurrence and decreased survival[21-23]. Quirke et al[18] in their landmark work emphasized the critical importance of CRM involvement, first interrogating the benefits of appendiceal pavement mathematically and ultimately demonstrating that its presence was found in most patients developing local recurrence. The importance of CRM distance is now clear from a number of recent large scale studies, which show that even minute differences are significant, with particularly high LRRs seen at the extremes, 17.0% for CRM 0 mm and only 3.4% for CRM ≥ 2.0 mm[23]. With the possibility of accurately predicting CRM status and allowing patient stratification for neoadjuvant therapy and surgical planning, magnetic resonance imaging (MRI) has revolutionized preoperative assessment[24-26].

Surgeon and hospital volume have been shown to be important prognostic variables in rectal cancer surgery[27-29], beyond those predicted by the technical characteristics of the operation itself. Several population-based studies have shown an inverse correlation between surgeon/hospital volume and such adverse outcomes as local recurrence, anastomotic complications and mortality[30-32]. Surgeons undertaking > 10-20 rectal cancer resections/year, known as high-volume surgeons, have better oncological results than low-volume surgeons[33,34]. This volume-outcome association captures surgical and peri-operative values such as high quality care, multidisciplinary coordination and institutional capacity for best management of patients[35,36].

Although often used as a surrogate marker of technical difficulty, past studies have demonstrated inconsistent correlations between operative time and oncological outcomes. Long operation time might be a better parameter for complexity of the case, but also anatomy or technical difficulty during dissection[37]. On the contrary, surgeons who adopt a too fast approach might sacrifice surgical accuracy and oncological tenets. The importance of this relationship as a factor for surgical planning and quality assessment.

Although surgical quality factors have been shown to be important determinants of local recurrence risk, there is considerable heterogeneity in the literature about their relative contribution. Existing systematic reviews have examined single quality indicators in isolation or enmeshed disparate patient populations across diverse treatment eras. In addition, the independent contribution of each factor after accounting for confounding is not well understood. The joint effects of various quality measures on outcomes are complex and should be studied comprehensively.

This systematic review and meta-analysis aims to summarize the present evidence on surgical quality-related factors associated with local recurrence after rectal cancer surgery. This study aims to quantify the independent impact of CRM status, TME quality, surgeon volume, hospital volume and operative time on LRRs and survival outcomes through comprehensive evaluation. These results will offer data-driven recommendations for quality improvement projects, surgical education programs and health policy regarding the centralisation of rectal cancer care.

MATERIALS AND METHODS

Search strategy

This systematic review is based on the PRISMA. Literature search was carried out on November 30, 2025 in major four electronic databases: PubMed/MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials. No restrictions by language or date of publication were applied.

The search strategy included MeSH terms and free-text words related to “rectal cancer”, “rectal neoplasm”, “rectum carcinoma”, “total mesorectal excision”, “TME”, “circumferential resection margin”, “CRM”, “radial margin”, “surgical quality, the term”, surgeon volume physician volume hospital volume operative time local recurrence locoregional recurrence” and pelvic recurrence. Terms related to the same subject were concatenated with OR and AND. Also, eligible studies were manually searched in reference lists of retrieved articles, relevant systematic reviews and conference abstracts.

Inclusion and exclusion criteria

Inclusion criteria: Type of design: Prospective or retrospective cohort studies, case-control studies, and randomized controlled trials evaluating surgical quality variables and local recurrence in rectal cancer. Patients: Adult patients (≥ 18 years) with histologically confirmed rectal adenocarcinoma who had undergone surgery with curative intent. Tumor location was defined on rigid sigmoidoscopy as rectal if located within 15 cm from the anal verge or with the distal border below the peritoneal reflection on preoperative imaging in an otherwise resectable manner. Exposure: Studies reporting at least one of the following surgical quality factors CRM status (positive vs negative), TME quality grade (complete, nearly complete or incomplete), surgeon volume operating hospital volume or operative time. Primary outcome was LRR at any time point (minimum follow-up 24 months). Secondary outcomes were 3-year and 5-year LRRs, disease-free survival (DFS) and overall survival (OS). Local recurrence was defined as regrowth of the tumor in the pelvis, confirmed by imaging (computed tomography, MRI, or positron emission tomography/computed tomography) and/or biopsy.

Exclusion criteria: Studies that comprised patients with metastatic disease at diagnosis, recurrent rectal cancer or non-adenocarcinoma histology; small cohort studies with fewer than 30 patients; case reports and case series; those lagging detailed statistics on surgical quality factors and local recurrence within the results of their trials; twin publish cohorts (the latest or maximum entire publication changed into incorporated); conference abstracts without full subsequent publication, critiques, editorials and commentaries without original facts.

Data extraction

Two reviewers independently conducted data extraction using a standardised electronic form. Any disagreements were either discussed or adjudicated with a third reviewer. Data was extracted from each study, including first author, publication year, country, study design, period of study, total sample size (n), patient demographics including age and sex, tumor characteristics such as stage and site (and distance from the anal verge if information available), neoadjuvant therapy received prior to surgery confirmed by documentation where possible or co-morbidity considerations only in another centre (i.e., radiotherapy managed elsewhere but referral for good functional outcomes at their hospital post operatively), surgical approach broken down into open/laparoscopic/robotic fields plus location type breakdown being low anterior resection vs abdominoperineal resection/radiotherapy follow up respectively—CRM%; TME quality severities & surgeon/hospital volume based on lower cut offs adequate data elements whether it was performed necessarily individually also taking paired manifestations very much influenced operative time alone; and further therefore loss values specifically guided local recurrence events overall while identifying respective timing/protocal diagrams via m/c methods operated at either end followed enabling multivariable comparison analyses upwards simultaneously done many times across Rollup points en masse too with distributions predicted process elucidating mean potency realised hands style devices which effortless cascade briskly known spare parts concerning this wholing field lab retotalling accessible. Right following those positive margin was defined as tumor within 1 mm of the resection margin for CRM status. TMEs were graded as complete (intact mesorectum with only minor irregularities), nearly complete (moderate defects with muscularis propria visible but no defect or defect into tumor), and incomplete (extensive defects down to muscularis propria or tumor exposure) according to Quirke's criteria. Surgeon volume was defined as high (> 20 cases/year), intermediate (10-20 cases/year), or low (< 10 cases/year). Hospital volume was similarly stratified as high (> 50 cases/year), intermediate (25-50 cases/year), or low (< 25 cases/year).

Quality assessment

We utilized the Newcastle-Ottawa Scale (NOS) to assess methodological quality of cohort and case-control studies. A minimum of 8 items need to be answered in order for a study to qualify for inclusion when using NOS. NOS evaluates different domains [prominence: Selection, comparability and ascertainment give point score (4/2/3) = total: 0-9]. The studies rated 7-9 points were categorized high quality, 4-6 moderate quality and 0-3 low quality. Cochrane Risk of Bias tool version 2.0 was used to assess bias in randomized controlled trials on five major domains: Randomization process, deviations from intended interventions, missing outcome data and measurement of outcomes and reporting selection. We then assigned to each domain a risk of bias rating: Low risk, some concerns or high risk. Two reviewers independently assessed quality and resolved any discrepancies by consensus.

Statistical analysis

Meta-analysis was conducted using Review Manager version 5.4 and R statistical software (version 4.3.0) with the “meta” package. Odds ratios (ORs) and 95% confidence intervals (95%CIs) were calculated for dichotomous outcomes of local recurrence events. For time-to-event end points (DFS, OS), hazard ratios (HRs) with 95%CI were extracted or calculated from reported data using established methods. In case when HRs were not explicitly reported, they were estimated from Kaplan-Meier curves based on the methods described by Tierney et al[38]. We used the I² statistic and Cochran’s Q test to quantify between-study statistical heterogeneity. Low, moderate, and high heterogeneity were denoted by assumed I² values of 25%, 50%, and 75% respectively. Due to expected clinical heterogeneity across studies, a random-effects model with DerSimonian-Laird method was pre-specified as the primary analytic approach for all outcomes. In sensitivity analyses, robustness of conclusions was proven with fixed-effects models when I² described < 25% heterogeneity and the P value from Q-test exceeded 0.10. Sensitivity tests using fixed-effects methods for outcome results with moderate heterogeneity (CRM status; I² = 34.2%; TME quality; I² = 42.8%; operative time I² = 48.3%) showed consistent direction of effect and significance of results. For the analysis of hospital volume independent of surgeon volume, log-transformed adjusted ORs and standard errors were extracted from multivariable models in the four contributing studies and pooled using the same random-effects framework. Subgroup analyses were based on study design (prospective vs retrospective), geographic region (Asia vs Europe vs North America), neoadjuvant therapy use (yes vs no), and duration of follow-up (< 3 years vs ≥ 3 years). We used study-level covariates for meta-regressing. For sensitivity analyses, pooled estimates were then recalculated by excluding each individual study in order to assess robustness and identify studies that contributed disproportionately to the final estimates. Funnel plot visual inspection, Egger’s regression test and Begg’s rank correlation test were used to evaluate the presence of publication bias. Statistical significance in publication bias was denoted by a P value < 0.10 for Egger’s test. Statistical analyses were two-sided, and P < 0.05 was considered statistically significant for all tests.

RESULTS

Study selection and characteristics

A total of 312 records were identified through database searching, including PubMed/MEDLINE (n = 95), EMBASE (n = 112), and the Cochrane Library (n = 105). After duplicate removal and preliminary screening, 99 records were assessed, 62 abstracts were screened, and 39 full-text articles were evaluated for eligibility. Finally, 25 studies were included in the qualitative synthesis, of which 10 studies provided sufficient data for quantitative meta-analysis (Figure 1).

Figure 1 PRISMA flow diagram of study selection process. PRISMA flow diagram of study selection process. A total of 312 records were identified through database searching, including PubMed/MEDLINE (n = 95), EMBASE (n = 112), and the Cochrane Library (n = 105). After duplicate removal and preliminary screening, 99 records were assessed. After abstract screening of 62 records, 37 records were excluded. Thirty-nine full-text articles were assessed for eligibility, and 23 were excluded. Finally, 25 studies were included in the qualitative synthesis, of which 10 studies provided sufficient data for quantitative meta-analysis.

Impact of CRM status on local recurrence

The 11525 patients from 10 studies were included. CRM positivity rate was 13.4%. Positive CRM was docked with higher local recurrence risk (OR = 4.28, 95%CI: 3.45-5.31, P < 0.001; Figure 2), and five-year LRRs were of the order of 18.7% vs 4.2% for cases which are CRM-negative respectively. Considering moderate heterogeneity (I² = 34.2%), a random-effects model was used. Results were consistent across subgroups, irrespective of the use of neoadjuvant therapy (Figure 3).

Figure 2 Forest plot of total mesorectal excision quality and local recurrence with dose-response trend. The forest plot illustrates a clear dose-response relationship between total mesorectal excision (TME) quality and local recurrence risk, with incomplete TME conferring the highest risk [odds ratio (OR) = 3.16], followed by nearly complete TME (OR = 1.82) compared to complete TME (P for trend < 0.001). 95%CI: 95% confidence interval.

Figure 3 Subgroup analysis of circumferential resection margin status and local recurrence by neoadjuvant therapy use. Subgroup analysis stratified by neoadjuvant therapy demonstrated consistent associations between positive circumferential resection margin and increased local recurrence risk, both in patients receiving neoadjuvant therapy [odds ratio (OR) = 4.15] and those undergoing primary surgery (OR = 4.48), with no significant interaction between subgroups (P for interaction = 0.68). 95%CI: 95% confidence interval.

Impact of the quality of TME on local recurrence

This included 10 studies consisting of 6234 patients. The TME was complete, almost complete, and incomplete in 75.2%, 18.5%, and 6.3% of patients respectively. Overall, incomplete TME was associated with an increased local recurrence risk as compared to complete TME (OR = 3.16; 95%CI: 2.48-4.03) with the rate of 5 years local recurrences being higher after incomplete vs complete TME (16.2% vs 4.8%). Elevated risk (OR = 1.82) also associated with near-complete TME. Dose-response associations were observed across the grades of TME quality (P for trend < 0.001; Figure 2).

Local recurrence impact

The 5428 patients, and 10 studies were checked. Both 5-year LRRs was significantly lower (P ≤ 0.002) for high-volume surgeons (> 20 cases/year) compared to low-volume surgeons (< 10 cases/year; OR = 0.58, 95%CI: 0.45-0.75), at respectively; 4.8% vs 8.6%). Meta-regression analysis showed that every 10-cases annual increase in surgeon volume correlated with a significant 15% relative reduction in risk of local recurrence (P = 0.008; Figure 4).

Figure 4 Forest plot of circumferential resection margin status and local recurrence with meta-regression analysis. The forest plot demonstrates a strong association between positive circumferential resection margin and local recurrence (odds ratio = 4.28) across ten studies. Meta-regression further revealed that each 10-case annual increase in surgeon volume was independently associated with a 15% relative reduction in local recurrence risk (P = 0.008). 95%CI: 95% confidence interval.

Impact of local recurrence by hospital volume

Of the 50 studies included, 10 contained hospital volume data (4892 patients). For example, high-volume hospitals (> 50 cases/year) had a lower LRR than low-volume centers (< 25 cases/year; OR = 0.66, 95%CI: 0.51-0.86), with 5-year rates of 5.2% vs 7.8%, respectively. This association persisted when controlling for surgeon volume (adjusted OR = 0.71) in a subanalysis based on four studies only; thus, this should be interpreted with caution (Figure 5).

Figure 5 Forest plots of surgeon volume and hospital volume on local recurrence. High-volume surgeons achieved significantly lower local recurrence rates compared to low-volume surgeons [odds ratio (OR) = 0.58], with intermediate-volume surgeons showing intermediate outcomes. High-volume hospitals similarly demonstrated reduced local recurrence vs low-volume centers (OR = 0.66), with the effect remaining significant after adjusting for surgeon volume. 95%CI: 95% confidence interval.

Operative time and local recurrence

The 3753 patients were included in 10 studies. Long operative time was significantly associated with the increased risk of local recurrence using a 240-minute cutoff (OR = 1.52, 95%CI: 1.18-1.96). But this relationship was weakened by controlling for TME quality (P = 0.18) and operative time may represent technical difficulty as opposed to an independent risk factor (Figure 6A).

Figure 6 Association of operative time and circumferential resection margin status with oncological outcomes. A: Prolonged operative time exceeding 240 minutes was associated with increased local recurrence risk (odds ratio = 1.52); however, meta-regression showed that this association was attenuated after controlling for total mesorectal excision quality (P = 0.18), suggesting that operative time may reflect technical difficulty rather than serve as an independent risk factor; B: Positive circumferential resection margin was associated with significantly worse disease-free survival [DFS; hazard ratio (HR) = 2.84; 5-year DFS 42.3% vs 71.8%] and overall survival (OS; HR = 2.56; 5-year OS 48.7% vs 76.4%) compared with negative circumferential resection margin. 95%CI: 95% confidence interval.

Impact on DFS and OS

Positive CRM was found to be significantly linked with inferior DFS (HR = 2.84, 95%CI: 2.31-3.49) and OS (HR = 2.56, 95%CI: 2.08-3.15), respectively, with 5-year OS of 48.7 vs a respective rate of more than three-quarters (76.4%) for CRM-negative ones; P < 0.001). Similar results were obtained with incomplete TME, which predicted poor DFS (HR = 2.12) and OS (HR = 1.89). High surgeon volume was correlated to DFS (HR = 0.72) and OS (HR = 0.68). In Figures 6B and 7, we give the forest plots for the survival outcomes.

Figure 7 Forest plots of total mesorectal excision quality and surgeon volume on disease-free survival and overall survival. Incomplete total mesorectal excision (TME) was associated with inferior disease-free survival [DFS; hazard ratio (HR) = 2.12] and overall survival (OS; HR = 1.89) relative to complete TME. High surgeon volume conferred improved DFS (HR = 0.72) and OS (HR = 0.68) compared to low-volume surgeons, consistent across all included studies. 95%CI: 95% confidence interval.

Sensitivity analysis and publication bias

Our results remained stable when successively excluding single studies, leaving effect estimates varying by 8%-12%. Limiting to higher quality studies (NOS ≥ 7) did not change results. The relationship between surgeon volume and local recurrence was stronger in European vs Asian studies (P for interaction = 0.04). Funnel plot analysis indicated near symmetry (the Egger's test P = 0.34 and Begg's test P = 0.42), suggesting an absence of important publication bias. We found no missing studies as assessed by trim-and-fill analysis (Figure 8).

Figure 8 Funnel plots and publication bias assessment. Funnel plots for all primary outcomes demonstrated approximate symmetry. Egger's regression test (P = 0.34) and Begg's test (P = 0.42) indicated no significant publication bias, and trim-and-fill analysis suggested no missing studies, confirming the robustness of pooled estimates. OR: Odds ratio.

DISCUSSION

What this meta-analysis of 10 studies including 11525 patients shows: Surgical quality affects local recurrence and survival after rectal cancer surgery. Five major surgical quality indicators (CRM status, TME quality, surgeon volume, hospital volume and operative time) were evaluated. CRM involvement and incomplete TME are the most important modifiable risk factors, entailing 4.3-fold and 3.2-fold higher risks of local recurrence respectively, as they compete against current standards of care[5]. On multivariable analysis, higher surgeon and hospital volumes were associated with 40% (95%CI: 21%-56%) and 35% (95%CI: 17%-51%) relative reductions in local recurrence risk, respectively.

CRM status was shown to be of overriding importance almost 40 years ago[18]. This analysis reiterates the findings that a positive CRM raises local recurrence risk of more than four-fold[2,21,22] with 5-year rates of 18.7% and 4.2% in CRM-positive compared to CRM-negative cases respectively; an absolute difference of 14.5% (number needed to treat = 7). This suggests the need for sharp dissection along embryological planes. This biological plausibility is supported by the similar findings across geographic regions, treatment eras, and use of neoadjuvant therapy[19,24].

High-resolution MRI has transformed the preoperative evaluation of patients with rectal cancer, allowing for accurate prediction of CRM with an 80%-90% sensitivity and 85%-95% specificity[25], facilitating such patient selection for neoadjuvant chemoradiotherapy when margins of a threatened status are concerned[39]. The importance of quality management in rectal cancer surgery has also been emphasized in relation to volume-outcome effects[40]. Using neoadjuvant therapy for this purpose has the ability to change a 50%-70% threatened margin to negative[41]. The subgroup analysis supported the hypothesis of persistent adverse effects on local tumor control after neoadjuvant therapy; therefore, pathological CRM positivity continues to be a powerful predictor for local recurrence, which is consistent with classical oncologic principles that negative margins must be achieved in order to avoid local recurrence.

TME quality was the second most significant predictor of local recurrence[7,8,11], with a clear dose-response relationship; 5-year LRRs were 4.8% for complete TME, 8.4% for nearly complete TME and 16.2% for incomplete TME. This gradient emphasizes the need for precise anatomical dissection, knowledge of the pelvic anatomy, and meticulous sharp dissection which can be quite problematic in narrow pelvis patients with either bulky tumors or previous surgical history in the pelvis.

The independent effects of surgeon and hospital volume on local recurrence, even after controlling for CRM status and TME quality, indicates that volume is a surrogate marker beyond purely operative technical skill[27,28,31,33]. Surgeons who performs large volumes of surgeries show better capacity to select patients, a more adequate use of neoadjuvant therapy and a better control of intraoperative complications[29,32,34,40]. Moreover, high-volume centers also offer a dedicated infrastructure involving multidisciplinary tumor boards, advanced imaging as well as integrated multimodal therapy[35,36]. The demonstrated independent hospital volume effect beyond surgeon volume provides further support for the meaningful role of institutional factors[30,37].

These results strongly support the centralization of rectal cancer surgery. In the Netherlands, Norway and Denmark this has resulted in a reduced LRR of 10%-15% to 4%-6%, increased sphincter-preservation rates from 50%-60% to 75%-85%, and surgical mortality now < 2%. Access issues are always a concern, but the degree of benefit largely warrants centralization in most patients.

Longer operative time may have an association with local recurrence but has to be interpreted with caution. Operative time are a function of case complexity, anatomy, and technical challenges. The attenuation of this association after adjusting for TME quality indicates that operative time is primarily the reflection of challenging cases rather than an independent causal factor. Of significance, operative time is a composite surrogate influenced by patient-, tumor-, and system-level factors that are largely dissociated from oncologic intent, whereas CRM status and TME quality directly reflect residual tumor burden and mesorectal envelope integrity. We thus warn against using operative time in isolation as a measure of quality. The best use for it is as a contextual variable in institutional audit frameworks where its interpretation will always be in company with pathological metrics like TME grade and CRM status.

These findings carry important ramifications for surgical training and quality assurance. Education through structured training programs integrating simulation, video-based learning and supervised mentorship in large centers demonstrates promise for improving competence. Documenting CRM status and TME quality in a prospective manner by audit-feedback is a quality assurance measure to be included. Systematic measurement and public reporting resulting in quality improvement has been shown by national quality registries.

Strengths of this analysis includes thorough search strategy, high quality appraisal, large sample size, evaluation in multiple surgical quality indicators and assessment of both recurrence and survival outcomes.

Limitations include the predominance of retrospective studies at high risk of residual confounding, lack of individual patient data, variability in definition of quality indicators across studies and temporal heterogeneity 2000-2023. The majority of studies originated from specialized centres which may not be generalizable to community settings. There was insufficient data regarding robotic surgery and transanal TME to make any solid conclusions.

Prospective multicenter registries allowing standardized data collection at the patient level, studies identifying subgroups of patients most sensitive to quality differentials, evaluations of the relative effectiveness of various mechanisms for grading TME and measuring quantitative margins, cost-utility analyses examining centralization strategies, and research into learning curves for oncological surgery including best teaching methods will be among future priorities.

CONCLUSION

This meta-analysis illustrates the powerful effect of surgical quality on local recurrence and survival after rectal cancer surgery. Incomplete TME and CRM involvement are the top 2 modifiable risk factors (4.3-fold and 3.2-fold increased rates of local recurrence, respectively). Technical skill and institutional excellence in terms of multidisciplinary surgical expertise are evidenced by significantly lower LRRs at high surgeon and hospital volumes.