Do the existing staging systems for primary liver cancer apply to combined hepatocellular carcinoma-intrahepatic cholangiocarcinoma?

The incidence of combined hepatocellular carcinoma-intrahepatic cholangiocarcinoma (cHCC-ICC) is relatively low, and the knowledge about the prognosis of cHCC-ICC remains obscure. In the study, we aimed to screen existing primary liver cancer staging systems and shed light on the prognosis and risk factors for cHCC-ICC.We retrospectively reviewed 206 cHCC-ICC patients who received curative surgical resection from April 1999 to March 2017. The correlation of survival measures with the histological types or with tumor staging systems was determined and predictive values of tumor staging systems with cHCC-ICC prognosis were compared.The histological type was not associated with overall survival (OS) (P = 0.338) or disease-free survival (DFS) (P = 0.843) of patients after curative surgical resection. BCLC, TNM for HCC, and TNM for ICC stages correlated with both OS and DFS in cHCC-ICC (all P 0.05). The predictive values of TNM for HCC and TNM for ICC stages were similar in terms of predicting postoperative OS (P = 0.798) and DFS (P = 0.191) in cHCC-ICC. TNM for HCC was superior to BCLC for predicting postoperative OS (P = 0.022) in cHCC-ICC.The TNM for HCC staging system should be prioritized for clinical applications in predicting cHCC-ICC prognosis.