A prognostic nomogram for pancreatic ductal adenocarcinoma patients’ all-cause survival in a Surveillance, Epidemiology, and End Results analysis

BACKGROUND: The American Joint Committee on Cancer (AJCC) staging system is not adequate for predicting the all-cause survival of patients with pancreatic ductal adenocarcinoma (PDAC). The aim of this study was to establish a comprehensive nomogram for PDAC and compare its prognostic ability with that of the AJCC 8th edition staging system. METHODS: This study identified 5,097 patients with PDAC in the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2016, and R software was used to divide them into training (n=3,567) and validation (n=1,530) cohorts. Multivariate Cox regression was used to select predictive variables. The concordance index (C-index), the area under the time-dependent receiver operating characteristics curve (AUC), the net reclassification improvement (NRI), the integrated discrimination improvement (IDI), calibration plotting, and decision-curve analysis (DCA) were used to compare the new survival model with the AJCC 8th edition prognosis model. RESULTS: After performing a multivariate Cox regression analysis, data on the age at diagnosis, marital status, primary site, pathology grade, regional nodes examined, AJCC stage, surgery status, adjuvant radiotherapy status, and adjuvant chemotherapy status were entered into the model and used to establish the nomogram. The C-index for the nomogram (0.668 for the training cohort and 0.670 for the validation cohort) was higher than those for the AJCC staging system (0.590 and 0.578, respectively). The AUC, NRI, IDI, calibration plotting, and DCA showed that the nomogram performed better than the AJCC staging system. CONCLUSIONS: We have developed and validated a prognosis nomogram as a predictive model for PDAC patients provides significantly improved predictive performance and is superior to the latest AJCC 8th edition staging system.