Prognostic Nomogram for Resected Pancreatic Adenocarcinoma: A TRIPOD-Compliant Retrospective Long-Term Survival Analysis

Abstract

Background: Prognostic prediction had been widely used in various cancer entities, from early screening to end-stage patient caring. Currently, there is hardly any well-validated nomogram which exists for long-term survival prediction in pancreatic adenocarcinoma (PC) patients in a post-surgery setting. Our objectives are to identify possible prognostic factors in PC patients following radical resection and to develop a prognostic nomogram based on independent survival predictors.

Methods: From 2009 to 2014, a total of 432 PC patients who underwent curative intended surgeries with complete follow-up data were included in this current retrospective long-term survival analysis. Clinicopathological data were extracted from medical records, and all missing values (percentage 0.9-8.3%) were imputed five times with the "PMM" method. Cox proportional hazards models were utilized. A nomogram was formulated based on results from the multivariate regression model so as to predict OS at 1-, 2- and 3-year as well as median OS. Validations, including discrimination and calibration, were carried out with 1000 bootstrap resamples. External validation was conducted in order to verify the accuracy of our nomogram at 1 and 2 years by utilizing the clinicopathological data of 122 PC patients who underwent curative intended surgeries in 2015 in our centre.

Results: Age, abdominal pain, back pain, tumour location, preoperative neutrophil-lymphocyte ratio, preoperative CA19-9, tumour differentiation, microscopic nerve invasion, microscopic vascular invasion, T stage, lymph node ratio, M stage and adjuvant chemotherapy were all assembled into nomogram. The concordance index (C-index) of internal and external validation was 0.702 and 0.688, respectively. The C-index of the TNM staging system was 0.572 (P < 0.001 vs. nomogram).

Conclusion: Our prognostic nomogram based on clinicopathological parameters shows good performance in long-term survival prediction in PC patients following radical surgery and could play a role in further clinical utilization.