Complete Mesocolic Excision Versus D2 Lymphadenectomy for Right Colon Cancer: A Bayesian Meta-Analysis of Randomized Trials Assessing Surgical and Perioperative Outcomes

Introduction: Complete mesocolic excision (CME) may increase lymph node retrieval and provide a more complete oncologic excision compared with D2 dissection, although its perioperative safety remains uncertain. This systematic review and Bayesian meta-analysis compared clinical and operative outcomes between CME and D2 in right colectomy. Methods: PubMed, EMBASE, and Cochrane Central were searched through November 2025. Randomized controlled trials comparing CME with D2 were included. Frequentist analyses used random-effects models with DerSimonian-Laird estimation. Bayesian random-effects models applied weakly informative priors (binary outcomes: log[RR] ∼ N(0, 1.5 2 ), τ ∼ Half-Normal(0.5); blood loss: μ ∼ N(0, 100 2 ), τ ∼ Half-Normal(100); lymph node yield: μ ∼ N(0, 6 2 ), and τ ∼ Half-Normal(3)). Heterogeneity was assessed using I 2 and Cochran’s Q. Analyses were conducted in R (v4.4.2) with bayesmeta. Results: Three randomized trials (1378 patients; CME 678, D2 700) met inclusion criteria. CME resulted in higher lymph node harvest (MD + 3.9; 95% CI: 2.8 to 5.0; P < .001) and longer operative time (MD + 11.6 minutes; 95% CI: 6.6 to 16.7; P < .001). No significant differences were found in blood loss, overall complications, severe complications, intraoperative complications, conversion, or 30-day mortality. Bayesian modeling provided very strong evidence for increased nodal yield (P[CME > D2] = 99.1%) and hemostatic equivalence (P[equivalent ± 50 mL] = 95.9%), with a modest probability favoring fewer severe complications (P[RR < 1] = 82.9%). Conclusion: CME offers superior oncologic radicality, reflected by higher lymph node retrieval, while maintaining perioperative outcomes equivalent to D2. Bayesian evidence reinforces CME as an effective and safe surgical strategy for right-sided colon cancer.