<b>Introduction:</b> The complications of surgical treatment for rectal cancer, particularly anastomotic leaks after anterior resection, are a significant clinical problem. We retrospectively analysed preoperative factors that may affect the occurrence of complications. <br><b>Meterial and Methods:</b> A total of 392 rectal cancer patients were included in a retrospective analysis. A total of 257 anterior resections (AR) and 135 abdominoperineal resections (APR) were performed. The risk factors for early postoperative complications were analysed by logistic regression and receiver operating characteristic curves. <br><b>Results:</b> The significant risk factors for severe complications (grade 3B and higher on the Clavien-Dindo scale) in the multivariate analysis were neutrophil to lymphocyte ratio > 5 (P = 0.047) in the AR group, age of the patients (P = 0.031) in the APR group, and coronary artery disease in both groups (P = 0.03, P = 0.011, respectively). There were no risk factors for anastomotic leaks in the AR group before the analysis was divided into early and late leaks. In the univariate analysis, the statistically significant risk factors for early leaks were preoperative neutrophil to lymphocyte ratio > 5 and peripheral blood platelet count, while late leaks were associated with coronary artery disease; however, in the multivariate analysis, these factors were not statistically significant. <br><b>Conclusions:</b> The risk factors for severe postoperative complications were neutrophil to lymphocyte ratio > 5, advanced age of the patients and coronary artery disease. The different risk factors for early and late anastomotic leaks after anterior resection may indicate their different aetiologies.
Keywords: anastomotic leak; anterior resection; postoperative complications; rectal cancer.