Cancer Incidence Rates Between BRCA1/2 Pathogenic Variant Carriers and Non-Carriers in Real-World Clinical Practice.

Since BRCA1/2 genetic testing has been covered by public insurance for certain breast cancer patients in Japan from April 2020, it has led to a rapid increase in testing frequency and the identification of many BRCA1/2 pathogenic variant (PV) carriers. BRCA1/2 PV carriers in Japan are reported to be also more susceptible to esophageal, gastric, and biliary tract cancers. We retrospectively analyzed 337 breast cancer patients who underwent BRCA1/2 genetic testing at Tohoku University Hospital. We extracted medical records such as past medical histories and family histories of malignancies based on questionnaires written by patient himself at first visit to our department. Compared to non-PV patients (n = 304), BRCA1/2 PV patients (n = 33) tended to have higher family history of breast cancer (P = 0.098) and had significantly higher family history of ovarian cancer (P = 0.005). However, pancreas, prostate, esophagus, gastric, and biliary tract cancer are not significantly more prevalent with family history among BRCA1/2 PV patients than non-PV patients. In following up on breast cancer patients with BRCA1/2 PV, at present, although there is a suggestion that esophageal, gastric, and biliary tract cancers are more likely to occur, the number of cases remains small, and it is not easy to perform these cancer screening on all BRCA1/2 PV cases.