Functional outcomes and quality of life after low anterior resection for rectal cancer: a retrospective cohort study comparing coloanal and colorectal anastomosis

Although anastomotic level after low anterior resection (LAR) for rectal cancer is largely determined by tumor location, its relationship with postoperative bowel function and quality of life remains clinically important. This study compared functional outcomes, fecal continence, sexual function, and health-related quality of life between patients undergoing colorectal anastomosis (CRA) and coloanal anastomosis (CAA) after curative-intent LAR. This retrospective cohort study included 126 patients who underwent LAR for rectal cancer between January 2019 and June 2024 (CRA, n = 84; CAA, n = 42). Health-related quality of life was assessed using the EORTC QLQ-C30 and QLQ-CR29 questionnaires, fecal continence using the Wexner score, and fecal incontinence-related quality of life using the FIQL scale in patients with Wexner scores > 8. Firth penalized logistic regression and multivariable linear regression were used to evaluate clinically significant fecal incontinence, Wexner scores, and selected EORTC domains, adjusting for age, sex, tumor level, neoadjuvant radiotherapy, diverting stoma, and time since surgery. Global health status was comparable between groups. In unadjusted analyses, the CAA group had higher stool frequency, flatulence, and embarrassment scores and a higher prevalence of clinically significant fecal incontinence than the CRA group (28.6% vs. 8.3%; p = 0.004). After adjustment, anastomosis type was not independently associated with clinically significant fecal incontinence (adjusted odds ratio, 2.30; 95% confidence interval [CI], 0.56–13.40; p = 0.261), Wexner score (adjusted β, 0.04; 95% CI, − 3.69 to 3.76; p = 0.984), global health status, or selected EORTC domains. No adjusted EORTC association remained significant after false discovery rate correction. Diverting stoma formation was independently associated with a higher Wexner score (adjusted β, 2.28; 95% CI, 0.61–3.95; p = 0.007). Sexual function did not differ significantly between groups. Although patients undergoing CAA had worse bowel function in unadjusted comparisons, these differences were not independently attributable to anastomosis type after adjustment for relevant clinical and treatment-related factors. Global quality of life was comparable between groups. Postoperative functional outcomes after rectal cancer surgery appear multifactorial and should not be attributed to anastomosis type alone.