FGFR2 and hilar cholangiocarcinoma: In the PRELUDE study [19], which investigated the expression rate of the FGFR2 fusion gene in biliary tract cancers in Japan, the FGFR2 fusion gene was found in 7.4% (20/272) of intrahepatic cholangiocarcinoma and 3.6% (3/83) of hilar cholangiocarcinoma, and was associated with young age (≤65 years: p = 0.070) and HCV/HBV infection (p = 0.037).