Introduction

Positive circumferential resection margin (CRM) after total mesorectal excision (TME) predicts higher local and systemic recurrence rates, affecting overall survival in rectal cancer patients. Although predictive factors for positive CRM have been identified for open, laparoscopic, and transanal TME, these may differ for robot-assisted TME (R-TME).

Aims & Methods

This study aimed to assess the incidence of positive CRM and to identify preoperative risk factors associated with this outcome following R-TME. An international multicenter retrospective study included patients receiving R-TME between January 2013 and January 2022 in participating Dutch, English, and French centers. Endpoints were the incidence of and predictive factors for positive CRM. Univariate and multivariate logistic regressions were performed, and factors associated with positive CRM were then assessed by formulating a predictive model.

Results

Of 1390 patients undergoing R-TME, the incidence of positive CRM was 6.0% (83 cases). Multivariate analysis revealed significant associations between positive CRM and tumors located up to 1 cm from the anorectal junction, cT4 tumors, cN+ tumors, and non-sphincter-saving surgery (odds ratios of 1.91, 3.04, 1.84, and 2.02, respectively). The predictive model exhibited satisfactory discrimination (area under the receiver-operating characteristic curve 0.71) and predicted a 37% risk of positive CRM when all identified risk factors were present.

Conclusion

Preoperative tumor- and procedure-related factors, rather than patient-related factors, significantly influenced CRM involvement after R-TME. The proposed predictive model allows preoperative calculation of the risk of positive CRM, offering valuable insights for optimizing patient selection and tailoring treatment approaches to enhance oncological outcomes.

Introduction

The standard surgical treatment for rectal cancer is total mesorectal excision (TME), which may negatively affect patients’ functional outcomes and quality of life (QoL). However, it is unclear how different TME techniques may impact patients’ functional outcomes and QoL.

Aims & Methods

This systematic review and meta-analysis evaluated functional outcomes of urinary, sexual, and fecal functioning as well as QoL after open, laparoscopic (L-TME), robot-assisted (R-TME), and transanal total mesorectal excision (TaTME). A systematic review and meta-analysis, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statements, were conducted (PROSPERO: CRD42021240851). A literature review was performed (sources: PubMed, Medline, Embase, Scopus, Web of Science, and Cochrane Library databases; end-of-search date: September 1, 2023), and a quality assessment was performed using the Methodological index for non-randomized studies. A random-effects model was used to pool the data for the meta-analyses.

Results

Nineteen studies were included, reporting on 2495 patients (88 open TME, 1171 L-TME, 995 R-TME, and 241 TaTME). Quantitative analyses comparing L-TME vs. R-TME showed no significant differences regarding urinary and sexual functioning, except for urinary function at three months post-surgery, which favored R-TME (SMD [CI] -0.15 [-0.24 – -0.06], p=0.02; n=401). Qualitative analyses identified most studies did not find significant differences in urinary, sexual, and fecal functioning and QoL between different techniques.

Conclusion

This systematic review and meta-analysis suggests no significant differences in patients' urinary, sexual, and fecal functioning and their QoL between various TME techniques. However, further high-quality, randomized-controlled, and prospective cohort studies are needed to confirm these findings.

Introduction

Aims & Methods

This retrospective cohort study encompasses all elective NRLAR, RLAR, and APR procedures performed for non-metastatic primary rectal carcinoma across 11 Dutch centers between 2013 and 2020. The primary outcome measured was 3-year disease-free survival (DFS), while secondary outcomes included 3-year overall survival (OS) and local recurrence (LR). Data analysis employed Kaplan-Meier survival analysis, and results were juxtaposed using log-rank testing. The association between resection type (NRLAR, RLAR, and APR) was further explored using multivariate Cox regression analysis.

Results

Conclusion

Disclosure

Introduction

Recent investigations have highlighted specific dimensions within the bony pelvis as potential indicators of total mesorectal excision (TME) outcomes. However, manual pelvimetry is labor-intensive.

Aims & Methods

This study endeavors to develop an automated pelvimetry system employing artificial intelligence (AI) to facilitate the preoperative identification of high-risk patients. Specifically, our research aims to construct and validate an AI-based automated pelvimetry tool and assess the prognostic utility of pelvimetric measurements in predicting postoperative complications necessitating reintervention (Clavien Dindo classification ≥ 3) in patients undergoing minimally invasive TME. This study is a multicenter retrospective cohort investigation incorporating clinical and imaging data from 1,700 patients treated at eight experienced TME centers. Leveraging a Deep-Learning network, our algorithm locates multiple anatomical landmarks to quantify pelvic inlet, pelvic outlet, and depth distances accurately. The accuracy of the developed algorithm is compared against inter-observer variability observed in manually conducted pelvimetry. The prognostic significance of pelvimetry for (post-)operative outcomes is evaluated through multivariate regression analyses.

Results

The AI-driven landmark localization achieved a mean margin of error of 5 millimeters across various pelvic dimensions, while manual pelvimetry demonstrated an inter-observer variation of 2.5 millimeters. Analyses of pelvimetric measurements and postoperative complications identified pelvic depth as an independent predictor of such complications (p < 0.001).

Conclusion

An artificial intelligence algorithm could successfully be used for accurate automated pelvic dimension determination. These pelvimetric measurements hold promise as a valuable decision support tool for surgeons in preoperatively assessing the risk of postoperative complications following minimally invasive TME.

Introduction

Endoscopic submucosal dissection (ESD) is widely recognized as the preferred technique for removing large benign colorectal lesions and those with a risk of submucosal invasive cancer (SMIC), with the goal of achieving en-bloc resection. R0 resection is crucial for enabling organ-preservation strategies, particularly in endoscopically resected T1-colorectal cancer (T1-CRC).

Aims & Methods

This study aims to evaluate R0 resection rates in a large cohort of colorectal ESDs by assessing vertical and lateral margins and identifying predictive factors for vertical margin involvement. Furthermore, the presence of other prognostic risk factors for lymph node metastasis (LNM) will be analyzed in this large cohort of T1-CRC. This is a multicenter prospective cohort study in 13 centers, including all colorectal ESDs between 09/2019 and 09/2024. Procedural and histological outcomes were analyzed using univariate and multivariate analysis.

Results

7495 large colorectal polyps were included, of which 781 were T1-CRCs with a median size of 45 [35-65] mm. En bloc resection occurred in 96.7% and R0 resection in 74.9%. Lateral resection margins were free in 92.5%, with positive margins for adenocarcinoma in only 0.8% (low grade dysplasia in 2.6%, high grade in 1.2%, missing data in 2.6%). Vertical margins were free in 80.3%, and decreased significantly when deep SMIC was present to 75.0%, compared to 95.7% for superficial SMIC. However deep SMIC with up to 2000 µm invasion depth, demonstrated free vertical resection margins in still 80.7%, after which it gradually decreased to 73.1% and 67.7% at an infiltration depth of 2000-3000 µm and >3000 µm respectively. Predictive factors for free vertical resection margins include lesion size >50mm (OR=1.66, [1.01;2.71], p=0.045) and rectal location (OR=1.86, [1.04;3.3], p=0.035). Significant difference was observed in the presence of prognostic risk factors for LNM between superficial and deep SMIC, with lympho-vascular invasion (LVI) being present in 9.6% and high-grade tumor budding (Bd) in 17.1% in superficial SMIC, compared to 25.0% and 30.0% respectively, in deep SMIC. However, absence of LVI, Bd or poor differentiation was noted in 75.9% of superficial and 61.7% of deep T1-CRC. Concerning deep SMIC, no relation was observed in the presence of these risk factors with respect to the depth of infiltration.

Conclusion

Following ESD for T1-CRC, the likelihood of achieving free vertical resection margins decreases significantly when invasion depth exceeds 2000 µm. Careful lesion selection through optical diagnosis is therefore critical. To push organ preservation, intermuscular dissection should be considered for T1-CRC with deeper invasion in the rectum. Achieving R0 resection remains paramount, as additional prognostic factors are present in approximately 38% of cases, irrespective of invasion depth.