BRCA1 and intrahepatic cholangiocarcinoma: BRCA1 mutations occur in 1% and BRCA2 mutations occur in 4% of patients with ICC.15)BRCA mutations have been used as biomarkers to predict the sensitivity to deoxyribonucleic acid-damaging therapies, platinum-based alkylating agents, in particular.16) Therefore, GCS therapy appears to be a particularly promising preoperative treatment for patients with ICC and BRCA mutations.