Development of a nomogram to predict overall survival in patients presenting with gastrointestinal neuroendocrine carcinoma (WHO G3).

Abstract

197 Background: To evaluate the prognostic factors in patients with gastrointestinal neuroendocrine carcinoma (WHO G3) (GI-NEC) and develop a nomogram to predict 1-year overall survival (OS). Methods: We performed a retrospective analysis of 122 patients with GI-NEC. Nomogram for 1-year OS was created as visualizations of Cox proportional hazards regression models and internally validated by use of bootstrap and cross-validation. We assessed nomogram model performance by examining overall accuracy (Brier score), calibration (calibration plot), and discrimination (Harrell C index). Results: The median survival was 9 months in 122 patients, and 51 (41.8%) patients died in the development cohort. A 1-year OS was chosen because 82% of the patients who died from disease did so within 1 year. Multivariable analysis identified prognostic factors including performance status, stage, Ki-67 index and LDH, all of which were included in the final model. In the development cohort, the Harrell C index for overall survival was 0·887 (95% CI 0·810-0·964), and calibration curves showed adequate calibration (judged by eye) of the observed and predicted probabilities. Conclusions: Prognostic factors were used to develop nomograms for 1-year OS for GI-NEC. The nomogram can be offered to clinicians to improve their abilities to assess patient prognosis, strengthen the prognosis-based decision making, enhance patient stratification, and inform patients in the clinic.