A Case of Bilateral Breast Cancer in which Cancer Multi-gene Panel Testing Contributed to Treatment

Abstract

Here, we report a case in which cancer multi-gene panel testing contributed to treatment. The patient was a 59-year-old woman. She was referred to our hospital for suspected left breast cancer with skin invasion. The right breast presented with invasive ductal carcinoma cT1N1M0 stage IIA (Luminal HER) and the left one with invasive ductal carcinoma cT4N3M0 stage IIIC (Luminal). The patient was treated with combination chemotherapy (docetaxel+pertuzumab+trastuzumab), and surgery was performed after tumor shrinkage was observed. Postoperatively, the patient was administered with adjuvant chemotherapy and endocrine therapy according to the subtype. One year postoperatively, treatment was switched due to the recurrence of bone metastases in the cervical and thoracic spine, followed by liver metastasis after 6 months. Liver biopsy was performed to reconfirm the subtype, and treatment was switched again. The patient was treated successfully, although adverse events rendered the continuation of treatment difficult after approximately 6 months. Therefore, cancer multi-gene panel testing (FoundationOne^®) was performed, and a germline mutation in the BRCA2 gene was confirmed. We strongly recommend the inclusion of multi-gene panel testing in cancer management, as it may offer new treatment opportunities.