HER2 assessment by bright‐field dual in situ hybridization in cell blocks of recurrent and metastatic breast carcinoma

Background Breast cancer recurrences or metastases often are diagnosed using cytology material. Cell blocks (CBs) with adequate cellularity are crucial for the determination of accurate hormonal and human epidermal growth factor receptor 2 (HER2) status and to guide treatment. In the current study, the authors evaluated the concordance of HER2 status between bright‐field dual in situ hybridization (DISH), fluorescence in situ hybridization...