Objective To investigate the influencing factors for low anterior resection syndrome(LARS)at one year after ileostomy reversal in patients who have undergone radical resection for rectal cancer,and to inform clinical interventions.Methods A retrospective cohort study was conducted on 312 patients who successfully underwent ileostomy reversal after radical resection for rectal cancer between January 2023 and January 2024 at 3 tertiary hospitals in Chongqing.Based on LARS scores at 1-year after stoma reversal,they were divided into a LARS group(score≥21)and a non-LARS group(score≤20).Clinical data were collected from the medical record system,including age,body mass index(BMI),sex,tumor size,tumor distance from the anal verge,T stage,N stage,date of low anterior resection,neoadjuvant therapy,postoperative chemotherapy,anastomotic leakage,and date of ileostomy reversal.Univariate analysis was used to screen potential influencing factors,and variables with P<0.2 were included in a multivariate logistic regression model.Binary stepwise regression analysis was applied to further analyze significant influencing factors for LARS at 1 year after ileostomy reversal.Results In the cohort,there were 127 patients assigned into the LARS group and 185 into the non-LARS group.The incidence of LARS at 1 year after ileostomy reversal was 40.70%,with mild cases accounting for 21.79%and severe ones for 18.91%,and a mean LARS score of 14.52±11.64.Multivariate logistic regression analysis showed that neoadjuvant therapy(yes vs no:OR=1.830,95%CI:1.088～3.089;P=0.023),tumor distance from anal verge≤5 cm(vs>5 cm:OR=2.044,95%CI:1.249～3.374;P=0.005),occurrence of anastomotic leakage(yes vs no:OR=7.470,95%CI:2.247～34.102;P=0.003),time to reversal(≥181 d vs 91～180 d:OR=2.297,95%CI:1.363～3.917;P=0.002),and N stage(N1～N2 vs N0:OR=1.650,95%CI:1.009～2.717;P=0.047)were significant influencing factors for LARS at 1 year after ileostomy reversal.Conclusion Our results suggest that anastomotic leakage,time to reversal≥181 d,tumor distance from anal verge≤5 cm,neoadjuvant therapy,and N stage N1～N2 are associated with the occurrence of LARS at 1 year after ileostomy reversal in patients following radical resection of rectal cancer.Clinical healthcare providers should implement early intervention and long-term follow-up for patients with high-risk factors both before and after stoma reversal.