Abstract
BACKGROUND: This study aimed to develop a nomogram to predict overall survival in anal squamous cell carcinoma (ASCC) patients undergoing chemoradiotherapy and to identify patients who may benefit from surgery. METHODS: Data from 4697 ASCC patients were extracted from the Surveillance, Epidemiology, and End Results database. Of these, 2657 patients were included in the training set, 1136 patients in the internal validation set, and 904 patients in the external validation set. LASSO and Cox multivariate regression analyses were conducted to identify independent prognostic factors and construct the nomogram. The discriminatory performance of the nomogram was evaluated using the time-dependent area under the receiver operating characteristic curve (ROC) and calibration curve. Decision curve analysis was used to compare the nomogram with the American Joint Committee on Cancer (AJCC) staging system. Additionally, a risk assessment system based on nomogram scores was developed. Propensity score matching and subgroup analysis were performed to identify groups with potentially better prognosis after surgery. RESULTS: Four independent variables-age, sex, tumor size, and AJCC stage-were identified as key predictors for the nomogram. The nomogram demonstrated robust discriminatory ability, as evidenced by the time-dependent ROC. Calibration plots showed strong concordance between the nomogram and real-world data in the training and validation cohorts, with the nomogram outperforming the AJCC staging system. Patients were stratified into subgroups based on their risk scores, revealing significant differences in overall survival between the subgroups (p < 0.05). Subgroup analysis suggested that males might benefit from surgery, which was not observed in females. CONCLUSION: This nomogram could serve as a valuable tool for clinicians in predicting long-term prognosis. We also identified patients who may benefit from surgery, providing a reference for treatment decisions in these patients.