ERBB2 and gallbladder cancer: Several studies also reported that the HER2 pathway could have a role in the development and growth of BTC (12–15) and HER2 overexpression and amplification were reported approximately 4–6% of BTC, 1–4% of intrahepatic cholangiocarcinoma, 4–9% of extrahepatic cholangiocarcinoma, and 9–14% of gallbladder cancer (11, 15, 16).