Impact of Surgical Approach, Patient Risk Factors, and Diverting Ileostomy on Anastomotic Leakage and Outcomes After Rectal Cancer Resection: A 5-Year Single-Center Study

Background and Objectives: This study aimed to evaluate surgical outcomes and identify prognostic factors associated with anastomotic leakage (AL), following rectal cancer resection. Materials and Methods: A retrospective cohort study included 415 patients who underwent rectal cancer surgery between 2020 and 2024. Patients were categorized by surgical approach (laparoscopic vs. open) and presence of AL. Results: Of the 415 patients, 160 (38.6%) underwent laparoscopic surgery, and 255 (61.4%) underwent open surgery. Operative time was significantly longer for laparoscopic surgery (213.0 ± 65.9 vs. 201.3 ± 60.4 min, p = 0.05), while stoma formation was more frequent in the open surgery group (60.0% vs. 48.1%, p = 0.018). Reoperation rate was higher in the laparoscopic group compared to the open group (13.1% vs. 6.7%, p = 0.027). The rate of AL was 20.5% in the laparoscopic group and 18.4% in the open surgery group (p = 0.434). Patients with AL had a significantly longer hospital stay (17 days, IQR 12.0–23.7 vs. 8 days, IQR 7.0–9.0, p < 0.001). The use of NOACs was associated with an increased risk of AL (p = 0.026). Multivariate analysis revealed that both a higher ASA score (p = 0.022) and older age (p = 0.044) were independent risk factors for AL, while the use of a diverting ileostomy was associated with a threefold reduction in the risk of AL (p = 0.049). Conclusions: AL rates were similar between approaches. Laparoscopic surgery had more reoperations and longer operative times. AL was associated with NOAC use, older age, and higher ASA scores. Diverting ileostomy reduced AL risk and warrants broader use in high-risk patients to improve outcomes.