[Analysis of the incidence and risk factors of low anterior resection syndrome after radical sphincter-preserving surgery for locally advanced rectal cancer treated with neoadjuvant immunotherapy: a single-center retrospective study].

Objective: To explore the impact of neoadjuvant immunotherapy on the occurrence of low anterior resection syndrome (LARS) in patients with locally advanced rectal cancer who underwent restorative anterior resection, and to analyze associated risk factors. Methods: This study was an observational study. Patients with adenocarcinoma, mucinous adenocarcinoma, or signet ring cell carcinoma of the rectum located 0-10 cm from the anal verge who received neoadjuvant immunotherapy followed by curative restorative anterior resection at Peking University Cancer Hospital between November 2019 and February 2024 were retrospectively examined. Exclusion criteria were as follows: (1) metastasis detected preoperatively;(2) follow-up <1 year or stoma closure <6 months; (3) local recurrence or metastasis during follow-up; and (4) stoma without closure or stoma re-creation. The Chinese version of the LARS questionnaire was used to assess bowel function by telephone interview, and patients were classified based on score into no LARS (0-20 points), minor LARS (21-29 points), and major LARS (30-42 points). The incidence of LARS, major LARS, and associated risk factors were analyzed. Results: A total of 52 patients (34 men) were included for analysis. Mean age was 58.0 ± 9.8 years and mean body mass index was 25.1 ± 2.6 kg/m². Median follow-up was 27.5 months (range, 12.0-63.7). Median LARS score was 21 (range, 1-41). Twenty-six patients (50.0%) developed LARS after surgery, and half of these (13 cases) were classified as major LARS. Stool clustering (repeated defecation within 1 hour) was observed in 80.8% (42/52) of patients. Distance between the tumor edge and the dentate line [odds ratio (OR), 3.597; 95% confidence interval (CI), 1.140-11.360; P=0.026], management of the left colic artery (OR, 0.133; 95% CI, 0.026-0.691; P=0.008), and interval of stoma closure (OR, 5.250; 95%CI, 1.381-19.960; P=0.011) were significantly associated with LARS. Interval of stoma closure was significantly associated with major LARS (OR, 4.200; 95%CI, 1.064-16.584; P=0.040). In multivariate logistic regression, ≤3.5 cm between the tumor edge and the dentate line (OR, 7.407; 95%CI, 1.377-40.000; P=0.020), non-preservation of the left colic artery (OR, 8.403; 95%CI, 1.183-58.823; P=0.033) and interval of stoma closure >6 months (OR, 10.865; 95% CI, 2.039-57.896; P=0.005) were independent risk factors for LARS. Interval of stoma closure >6 months (OR, 4.356; 95% CI, 1.105-17.167; P=0.035) were independent risk factors for major LARS. Conclusion: Patients with locally advanced rectal cancer treated with neoadjuvant immunotherapy experienced a high incidence of LARS after curative surgery, with stool clustering as the predominant symptom. Tumor edge-dentate line distance ≤3.5 cm, non-preservation of the left colic artery, and interval of stoma closure >6 months were risk factors for LARS.