In a breast cancer patient with HER2+/ER+/PR+ subtype, simultaneous detection of HER2/PR expression by triple IF (HER2/PR/Hoechst) and cytokeratin expression of CTCs by ICC could be confirmed (Fig. 3C), indicating the potential utility of this method for the identification of breast cancer subtypes in the clinical setting. The gene discussed is ESR1; the disease is intrahepatic cholangiocarcinoma.