Individualized prediction of survival benefits from perioperative chemoradiotherapy for patients with resectable gastric cancer.

BACKGROUND The survival benefits of perioperative chemoradiotherapy (PCRT) and perioperative chemotherapy (PCT) for resectable gastric cancer (GC) patients remain unclear. This study aimed to compare the effects of PCRT and PCT in patients with resectable GC and develop a nomogram to evaluate the prognosis and disease risk of patients. METHODS A total of 6890 patients with stage IB-IIIC GC from 2010 to 2015 were retrieved from the Surveillance, Epidemiology and End Results (SEER) database. Univariate Cox proportional hazards regression analyses were performed to evaluate the prognostic value of involved variables. A new nomogram was constructed based on development cohort and validated by an external validation cohort. The clinical practicability and accuracy were assessed by concordance index (C-index), calibration plot, and receiver operating characteristic (ROC) curve. RESULTS A better prognosis was obtained for patients with stage III GC treated with PCRT compared with those treated with PCT. Additionally, patients with grade III/IV, diffuse type GC, distal gastric cancer (DGC), tumor size >34 millimeters, or positive lymph nodes were more likely to benefit from PCRT. Multivariate analyses indicated that age, grade, tumor size, T stage, N stage, and comprehensive treatment were independent covariates. Excellent agreement of calibration plots and good discrimination power were obtained using the nomogram. The nomogram achieved a better net benefit than the 8th edition AJCC TNM staging. An online version was built based on the nomogram for convenient clinical use. CONCLUSION The application of perioperative chemoradiotherapy should be determined according to the clinicopathological features of patients. Our nomogram provided a reliable tool for screening patients who were right for PCRT and evaluating individual survival benefits.