Proposal to modify the International Union Against Cancer staging system for perihilar cholangiocarcinomas

BACKGROUND: The International Union Against Cancer (UICC) staging system for perihilar cholangiocarcinoma changed in 2009. The aim of this study was to validate and optimize the UICC system for these tumours. METHODS: This retrospective study was conducted in eight Japanese hospitals between 2001 and 2010. Perihilar cholangiocarcinoma was defined as a cholangiocarcinoma that involves the hilar bile duct, independent of the presence or absence of a liver mass component. The stratification ability of the UICC tumour node metastasis (TNM) system was compared with that of a modified system. RESULTS: Of 1352 patients, 35.9, 44.8 and 12.6 per cent had Bismuth type IV tumours, nodal metastasis (N1) and distant metastasis (M1) respectively. T4 tumours (43.2 per cent) and stage IVA (T4 Nany M0; 36.3 per cent) disease were most common. Survival was not significantly different between patients with T3 versus T4 tumours (P = 0.284). Survival for patients with stage IVA disease was comparable to that for patients with stage IIIB tumours (T1-3 N1 M0) (P = 0.426). Vascular invasion, pancreatic invasion, positive margin, N1 and M1 status were identified as independent predictors of survival. When Bismuth type IV tumours were removed from the T4 determinants and N1 tumours grouped together, the modified grouping had a higher linear trend χ2 and likelihood ratio χ2 compared with the original system (245.6 versus 170.3 respectively and 255.8 versus 209.3 respectively). CONCLUSION: The present data suggest that minimal modification with removal of Bismuth type IV tumours from the T4 determinants and bundling of N1 disease may enhance the prognostic ability of the UICC system. However, this requires validation on an independent data set.