Hereditary Breast Cancer : The Difference between Genetic Medicines of Hereditary Cancer Syndrome and Genetic Testing as Companion Diagnostics

Abstract

As awareness of hereditary breast and ovarian cancer syndrome spreads in Japan, Japanese medical providers screen patients with breast and/or ovarian cancer with high genetic risk according to their personal and family histories in daily medical practice. They then ask genetic specialists, i.e., genetic counselors and geneticists, to provide genetic counseling and support their decision made regarding genetic testing. Depending on the interpretations of genetic test results, medical providers provide patients with appropriate medical management.

Olaparib (Lynpaza^®), a poly (adenosine diphosphate-ribose) polymerase inhibitor, was approved for treatment by the Japanese Ministry of Health, Labor and Welfare in July 2018 for patients with germline BRCA-mutated, HER2-negative metastatic breast cancer who had undergone chemotherapy. At the same time, BRCA genetic testing (BRCAnalysis^®) was also approved as a companion diagnostic. Thereafter, opportunities on obtaining informed consent for BRCA genetic testing by breast cancer oncologists were increasing, and they were required to disclose the interpretation of genetic test results to patients in some cases.

In these circumstances, surgeons in breast cancer must acquire and understand basic knowledge of hereditary cancer syndromes. Herein, the present situation surrounding genetic services for hereditary breast cancer are described, along with points for which we should take caution, accompanied by genetic tests as a companion diagnostic.