Comparison of the prognostic accuracy of the sixth and seventh editions of the TNM classification for intrahepatic cholangiocarcinoma

BACKGROUND: The seventh TNM edition introduced a new, specific staging structure for intrahepatic cholangiocarcinoma (IHC). OBJECTIVE: To compare the accuracy of the sixth and the new seventh edition to predict survival after hepatectomy for IHC. METHODS: In all, 434 consecutive patients who underwent hepatectomy at 16 tertiary-care centres (1990-2008) were identified. End points were overall (OS) and recurrence-free survival (RFS) for both T cohorts and stage strata. RESULTS: After a median follow-up of 32.4 months, 3- and 5-year OS and RFS estimates were 47.1% and 32.9%, and 26.5% and 19.1%, respectively. Overall, both the editions were statistically significant discriminators of OS and RFS (P < 0.05). However, the survival curves of the new T2a and T2b cohorts appear superimposed. Conversely, the old T2 and T3 cohorts accurately stratify patients into distinct prognostic groups (P < 0.01). The seventh edition does not show monotonicity of gradients (the T4 category demonstrates significantly better OS and RFS compared with T2 patients). The seventh edition stage I and II are significantly different whereas the old stage I and II were not. CONCLUSIONS: The new seventh edition of the AJCC/UICC Staging System proved to be adequate although further studies are need to confirm its superiority compared with the previous edition.