A systematic review, meta-analysis and GRADE assessment of the evidence on complete mesocolic excision for right-sided colon cancer with SAGES and ESCP participation.

Background: Complete mesocolic excision (CME) is a surgical approach for right-sided colon cancer, involving the resection of the primary tumour along with an intact mesocolon, central vascular ligation, and exposure of the superior mesenteric vein. It has been postulated to improve oncologic outcomes such as disease-free survival and reduce local recurrence compared to standard right colectomy. However, the clinical benefits are still debated.

Objective: This systematic review and meta-analysis, sponsored by the European Association for Endoscopic Surgery, aims to compare the oncologic outcomes of CME with standard right colectomy for right-sided colon cancer, with the ultimate objective to inform clinical practice recommendations.

Methods: We followed the PRISMA 2020 reporting standards. A comprehensive literature search was conducted to identify relevant studies published from 2008 onwards, focusing on randomised trials and matched cohort studies comparing CME with standard right hemicolectomy. The GRADE methodology was used to assess the certainty of evidence, and minimal important differences were calculated to inform clinical relevance.

Results: Thirteen studies, amongst which three randomised trials, were included. No difference was found between CME and standard colectomy in terms of 30-day mortality, major peri-operative morbidity, or major blood loss. However, patients who underwent CME showed improved overall survival (HR = 0.67, 95%CI [0.48 - 0.93], low certainty of evidence) and disease-free survival (HR = 0.78, 95% CI [0.63 - 0.96], low certainty of evidence) compared to those who underwent standard colectomy, though certainty of the evidence was low due to the high risk of bias in the observational studies.

Conclusion: Complete mesocolic excision may offer survival benefits over standard right colectomy for right-sided colon cancer. However, the evidence remains of low certainty, mainly due to the predominance of observational data with significant risk of bias. Future high-quality randomized trials are needed to confirm these findings and standardize surgical techniques to reduce heterogeneity and improve clinical outcomes.