Though a hepatectomy is frequently performed during surgery for BTC, it is unclear if the effect of the anticancer agent is affected by a hepatectomy. Because GEM is metabolized by cytidine deaminase primarily in the liver, the ability to metabolize GEM after a hepatectomy is thought to decrease. Some clinical studies demonstrated that patients who had undergone a hepatectomy could not tolerate the standard dose and schedule of GEM. For adjuvant chemotherapy with GEM, it is necessary to separately examine whether or not the patient has undergone a hepatectomy.