Development and validation of a prognostic nomogram for gallbladder cancer patients after surgery

Background Gallbladder cancer is associated with late diagnosis and poor prognosis. Current study aims to develop a prognostic nomogram for predicting survival of gallbladder cancer patients after surgery. Methods Two large cohorts were included in this analysis. One consisted of 1753 gallbladder cancer patients from the Surveillance, Epidemiology, and End Results (SEER) database, and the other consisted of 239 patients from Shanghai Renji hospital. Significant prognostic factors were identified and integrated to develop the nomogram. Then the model was subjected to bootstrap internal validation and external validation. Results Univariate and multivariate analysis indicated that age, tumor histology, T-stage, N-stage and M-stage were significant prognostic factors, which were all included to build the nomogram. The model showed good discrimination, with a concordance index (C-index) of 0.724 (95% CI, 0.708-0.740), and good calibration. Application of the nomogram in the validation cohort still presented good discrimination (C-index, 0.715 [95% CI 0.672-0.758]) and good calibration. In the primary cohort, the C-index of the nomogram was 0.724, which was significantly higher than the Nevin staging system (C-index = 0.671; P < 0.001) and the 8th TNM staging system (C-index = 0.682; P < 0.001). In the validation cohort, the C-index of the nomogram was 0.715, which was also higher than the Nevin staging system (C-index = 0.692; P < 0.05) and the 8th TNM staging system (C-index = 0.688; P = 0.06). Conclusions The proposed nomogram resulted in more-accurate prognostic prediction for patients with gallbladder cancer after surgery.