Yadav S, et al. - Existing staging systems for gallbladder cancer (GBC) are insufficient because they are based on surgical pathology, and therefore not pertinent to unresectable patients and patients undergoing neoadjuvant chemotherapy, so researchers developed a novel clinically-based staging system for patients with GBC. They found that this new staging system performed on par with the current surgical pathology based TNM staging system. This novel staging system was based on nonoperative information at the time of diagnosis.

Methods

• Participants included patients with a confirmed diagnosis of GBC who were seen at Mayo Clinic between 2000 and 2016.
• Retrospective review of electronic medical records provided data on demographic and tumor characteristics and outcomes.
• Cox proportional hazard regression analysis was used to develop a model predictive of overall survival.
• The predictive accuracy of the model was calculated using Harrel’s C-statistic and comparisons with the TNM staging system were carried out.

Results

• With a median age of diagnosis of 68 years, 523 patients were ultimately analyzed.
• The median duration of follow-up in the entire cohort was 12 months.
• The predictors of poorer overall survival identified in multivariate analysis were ages 65-74 years (HR : 1.80, 95% CI: 1.33–2.43) and ages 75+ years (HR: 2.93, 95% CI: 2.12–4.06) vs age <55 years; tumor size ≥ 5 cm by imaging (HR: 1.24, 95% CI: 1.01–1.55); nodal involvement by imaging (HR:1.61, 95% CI: 1.23–2.10); involvement of distant organs by imaging (HR: 2.85, 95% CI: 2.16–3.75); ECOG performance score of 2 or higher (HR: 1.78, 95% CI: 1.36–2.32) vs ECOG 0-1; albumin level <3.5 g/dL (HR: 1.40, 95% CI: 1.08–1.81); and alkaline phosphatase level ≥ 200 IU/L (HR: 1.49, 95% CI: 1.21–1.84).
• A four-tier staging system was developed by using these seven predictive factors of survival.
• In this novel system, 64, 34, 20 and 7 months were the median survivals of Stages I, II, III and IV, with corresponding hazard ratios of 1, 1.5, 2.5 and 8.5 respectively.
• The C-statistic for this novel staging system and for the TNM staging system was 0.68 and 0.69, respectively, this was suggestive of a similar performance in predicting survival.