Risk factors for anastomotic leakage after anterior resection for rectal cancer (RALAR study): A nationwide retrospective study of the Italian Society of Surgical Oncology Colorectal Cancer Network Collaborative Group

Aim: Anastomotic leakage after restorative surgery for rectal cancer shows high morbidity and related mortality. Identification of risk factors could change operative planning, with indications for stoma construction. This retrospective multicentre study aims to assess the anastomotic leak rate, identify the independent risk factors and develop a clinical prediction model to calculate the probability of leakage. Methods: This study used data from 24 Italian referral centres of theColorectal Cancer Network of the Italian Society of Surgical Oncology. Patients were classified into two groups, AL (anastomotic leak) or NoAL (no anastomotic leak). The effect ofpatient-, disease-, treatment- and postoperative outcome-related factors on anastomotic leak after uni- and multivariable analysis was measured. Results: A total of 5398 patients were included, 552 in group AL and 4846 in group NoAL. The overall incidence of leaks was 10.2%, with a mean time interval of 6.8 days. The 30-day leak-related mortality was 2.6%. Sex, BMI, No cartridges, operating time, type of approach, tumour location, combined multiorgan resection, pT and pN, were identified as independent risk factors. The stoma didn't reduce the leak rate, but significantly decreased leak severity and reoperation rate. A nomogram with a risk-score (RALARscore) was developed to predict anastomotic leak risk at the end of resection. Conclusions: While a defunctioning stoma did not affect the leak risk, it significantly reduced its severity. Surgeons should recognize independent risk factors for leaks at the end of rectal resection, and could calculate a risk-score to select high-risk patients eligible for protective stoma construction.