Objective To explore the impact of preventive stoma on the occurrence and development trajectory of low anterior resection syndrome (LARS) following rectal cancer surgery. MethodsA retrospective cohort study design was employed to collect clinical data from 540 patients who underwent rectal cancer resection at West China Hospital, Sichuan University between April 2018 and June 2022. Patients were categorized into stoma group (n=275) and non-stoma group (n=265) based on the presence or absence of preventive stoma. Generalized estimating equation was used to analyze the impact of stoma-related factors (presence of stoma, stoma type, and interval to stoma closure) on the occurrence of LARS at 1, 3, 6, 9, and 12 months postoperatively. Latent class growth modeling was employed to identify LARS development trajectories, and multi-class logistic regression was used to assess the influence of stoma-related factors on LARS trajectory categories. ResultsThe incidence of LARS showed an overall downward trend within 12 months postoperatively, the incidence rates at 1, 3, 6, 9, and 12 months after operation were 46.3% (250/540), 36.5% (197/540), 27.8% (150/540), 23.0% (124/540) and 16.9% (91/540), respectively. Generalized estimating equation analysis revealed that preventive stoma (OR=1.410, P=0.283), stoma type (OR=1.375, P=0.099), and interval to stoma closure (OR=0.999, P=0.502) were not independent predictors of LARS occurrence. Conversely, at various postoperative time points, educational level (junior college vs. bachelor’s degree or higher: OR=1.834, P=0.039), TNM (stage 2 vs. stage 4: OR=0.533, P=0.016; stage 3 vs. stage 4: OR=0.556, P=0.015), tumor length (OR=1.316, P=0.015), tumor width (OR=0.707, P=0.009), and surgical procedure (ultra-low anterior resection vs. coloanal anastomosis/colon anal anastomosis: OR=2.076, P=0.017) were closely associated with the occurrence of LARS. Latent class growth modeling identified three LARS trajectory categories: low symptom burden–rapid improvement group (286 cases, 53.0%), high symptom burden–slow improvement group (163 cases, 30.2%), and high symptom burden–persistent impairment group (91 cases, 16.8%). Multi-class logistic regression analysis revealed that the presence or absence of preventive stoma was not a predictive factor for LARS trajectory category (high symptom burden–slow improvement group: OR=0.739, P=0.407; high symptom burden–persistent impairment group: OR=0.693, P=0.400). However, patients undergoing ultra-low anterior resection were more likely to be assigned to the high symptom burden-slow improvement group (OR=2.677, P=0.026).ConclusionsPreventive stoma is not an independent risk factor for the occurrence or trajectory of LARS. The occurrence of LARS is associated with the tumor’s biological characteristics, surgical approach, and postoperative time, moreover, the surgical approach is a key factor influencing the progression of LARS.