Development and External Validation of a Model to Predict Overall Survival in Patients with Resected Gallbladder Cancer.

Objective The aim of this study was to develop and validate a clinical prediction model to predict overall survival in patients with non-metastatic, resected gallbladder cancer (GBC). Background Although several tools are available, no optimal method has been identified to assess survival in patients with resected GBC. Methods Data from a Dutch, nation-wide cohort of patients with resected GBC was used to develop a prediction model for overall survival. The model was internally validated and a cohort of Australian GBC patients who underwent resection was used for external validation. The performance of the AJCC staging system and the present model were compared. Results In total, 446 patients were included; 380 patients in the development cohort, and 66 patients in the validation cohort. In the development cohort median survival was 22 months (median follow-up 75 months). Age, T/N classification, resection margin, differentiation grade and vascular invasion were independent predictors of survival. The externally validated c-index was 0.75 (95%CI 0.69-0.80), implying good discriminatory capacity. The discriminative ability of the present model after internal validation was superior to the ability of the AJCC staging system (Harrell's C-index 0.71, (95%CI 0.69-0.72) versus 0.59 (95%CI 0.57-0.60)). Conclusion The proposed model for the prediction of overall survival in patients with resected GBC demonstrates good discriminatory capacity, reasonable calibration and outperforms the authoritative AJCC staging system. This model can be a useful tool for physicians and patients to obtain information about survival after resection and is available from https://gallbladderresearch.shinyapps.io/Predict_GBC_survival/.