Validation of a nomogram for selecting patients for chemotherapy after D2 gastrectomy for cancer

Abstract Background According to some guidelines for the management of gastric cancer, adjuvant chemotherapy is recommended for patients with pT3–4 or node-positive disease. The aim of this study was to define low- and high-risk groups in terms of survival, and to predict the benefit of adjuvant fluoropyrimidine plus oxaliplatin (F-OX) chemotherapy. Methods Patients with pT3–4 or node-positive gastric cancer after gastrectomy with D2 lymphadenectomy between 2000 and 2013 were included. The performance of a previously published nomogram was assessed by discrimination and calibration. Patients were stratified into risk groups on the basis of the nomogram-predicted overall survival probability. The efficacy of F-OX within each risk subgroup was assessed using the log rank test and Cox regression analysis weighted by inverse propensity score. Results Some 1464 patients were included. The nomogram showed better discrimination than the seventh AJCC staging classification (concordance index 0·72 versus 0·68 respectively; P = 0·008) and accurate calibration. F-OX was not associated with improved survival in patients in the low-risk group, whereas it reduced the risk of death by over 20 per cent in the intermediate- and high-risk groups (P = 0·036 and P < 0·001 respectively) (P for interaction = 0·014). Conclusion A nomogram can aid in individualized decision-making regarding the administration of F-OX after gastrectomy for cancer.