Construction and validation of a nomogram for predicting disease-free survival after radical resection of rectal cancer using perioperative inflammatory indicators.

Background: Colorectal cancer is a common digestive tract malignancy that seriously affects patients' quality of life and survival time. Surgery is the main treatment modality, but postoperative prognosis varies greatly. This study sought to explore the impact of perioperative inflammatory indicators on disease-free survival (DFS) in patients after radical resection of rectal cancer and to construct a nomogram for clinical reference. Methods: A retrospective analysis was performed on 304 primary rectal adenocarcinoma patients who underwent laparoscopic radical resection of rectal cancer at the Affiliated Hospital of Xuzhou Medical University from May 1, 2018 to September 30, 2020. The patients were divided into a training set (n=213) and a validation set (n=91) at a ratio of 7:3. The cut-off values of each inflammatory indicator based on the receiver operating characteristic (ROC) curve were determined and each indicator was divided into high and low groups. The least absolute shrinkage and selection operator (LASSO)-Cox regression model was used to analyze the independent risk factors affecting DFS, and a nomogram was established. The model was internally validated using the validation set, and the discrimination, calibration, and clinical application value of the nomogram were evaluated using ROC curve, calibration curve, and clinical decision curve analysis (DCA). Results: Tumor-node-metastasis (TNM) stage III, neural invasion, preoperative neutrophil-to-lymphocyte ratio (NLR) ≥1.995, postoperative systemic immune-inflammation index (SII) ≥451.05, and Δpan-immune-inflammation value (ΔPIV) ≥144.36 (P<0.05) were independent factors for predicting the 3-year DFS of patients after rectal cancer surgery. The area under the ROC curve (AUC) of the nomogram was 0.811 [95% confidence interval (CI): 0.778-0.889] in the training set and 0.808 (95% CI: 0.785-0.942) in the validation set. The nomogram showed good calibration, indicating good consistency between predicted and actual risks. DCA demonstrated the clinical utility of the nomogram. Conclusions: The nomogram constructed based on TNM stage III, neural invasion, preoperative NLR ≥1.995, postoperative SII ≥451.05, and ΔPIV ≥144.36 can predict the risk of 3-year DFS in patients undergoing curative surgery for rectal cancer, enabling strict postoperative follow-up and timely adjuvant treatment for high-risk patients.