Postoperative Outcomes After Rectal Cancer Surgery With or Without Primary Anastomosis: A Propensity Score–Weighted Study

Background: The role of primary anastomosis in rectal cancer surgery remains debated, particularly due to concerns regarding postoperative morbidity. Evidence from randomized trials is limited, and observational studies are frequently affected by selection bias. Methods: We conducted a retrospective observational study including patients undergoing rectal cancer surgery with or without primary anastomosis. To reduce confounding, propensity scores were estimated using relevant clinical and oncologic covariates, and overlap weighting was applied to estimate treatment effects in a population with clinical equipoise. The primary outcome was any postoperative complication. Secondary outcomes included severe postoperative complications, reintervention, in-hospital mortality, and measures of healthcare resource utilization. Absolute risk differences (RDs) and mean differences (MDs) with 95% confidence intervals (CIs) were calculated. Stabilized inverse probability of treatment weighting was used as a sensitivity analysis. Results: A total of 173 patients were included. After overlap weighting, primary anastomosis was not associated with a statistically significant difference in overall postoperative complications compared with no anastomosis (RD +0.01, 95% CI −0.14 to +0.17). Severe postoperative complications were numerically more frequent in the primary anastomosis group, while reintervention rates were numerically lower; however, these differences did not reach statistical significance. In-hospital mortality was significantly lower among patients undergoing primary anastomosis (RD −0.08, 95% CI −0.16 to −0.02). No significant differences were observed in length of hospital stay or intensive care unit utilization. Conclusions: Postoperative outcomes after rectal cancer surgery appeared broadly comparable between patients managed with or without primary anastomosis after adjustment for measured baseline characteristics. These findings should be interpreted in the context of residual confounding and surgical selection, and support individualized decision-making rather than routine use of either restorative or non-restorative strategy.