Association between 12 composite inflammatory indices and postoperative complications in colorectal cancer surgery: a two-center retrospective study

Background: Postoperative complications (POCs) remain a major challenge in colorectal cancer (CRC) surgery. Easily accessible composite inflammatory indices derived from routine blood tests hold promise for preoperative risk stratification, but their comparative predictive value for POCs is unclear. Methods: We conducted a two-center, retrospective study of 1331 patients who underwent radical CRC surgery between January 2021 to October 2025. The associations between preoperative composite inflammatory indices and the complications after surgery were evaluated using logistic regression. Their predictive discriminative performances were further assessed and compared using receiver operating characteristic (ROC) curve analysis, with the areas under the curve (AUC) compared by DeLong's test. Results: < 0.05). Conclusion: The SII, NLR, CLR and SIRI, are strongly associated with the risk of POCs after CRC surgery. A model combining these four indices provides superior predictive performance.