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This study aimed to clarify the breast cancer prognosis in Japanese patients with BRCA1/2 pathogenic variant. We analyzed 2235 women with breast cancer who underwent BRCA1/2 genetic testing between 1996 and 2018 using data from the Japanese hereditary breast and ovarian cancer syndrome registry. The cumulative risk for contralateral and ipsilateral breast cancers and time to death since the first breast cancer were stratified based on the BRCA1/2 variant status. The median follow-up was 3.0 years (0.1-34.1 years) after the first breast cancer. The annual average risks of contralateral breast cancer in BRCA1 and BRCA2 and non-BRCA1/2 pathogenic variant carriers were 4.0%, 2.9%, and 1.9%, respectively (P = 0.001). The annual average risks of ipsilateral breast cancer in the three groups were 2.7%, 1.4%, and 1.1%, respectively (P = 0.06). BRCA1 pathogenic variant carriers had significantly higher risks of contralateral (hazard ratio 1.91, P < 0.001) and ipsilateral (hazard ratio 2.00, P = 0.02) breast cancers than non-BRCA1/2 pathogenic variant carriers. The time to death by the BRCA1/2 variant status was not significantly difference (P = 0.28). The prognosis of breast cancer patients who received standard treatment was comparable regardless of the BRCA1/2 variant status.

Background: We studied the extent of BRCA1/2 genetic testing to help select the surgical approach for patients with breast cancer in Japan remains unclear., Patients and Methods: The study subjects were female patients with primary unilateral invasive breast cancer considered as candidates for breast-conserving surgery who underwent preoperative BRCA1/2 genetic testing. A retrospective analysis was performed on the results of BRCA1/2 genetic testing and surgical method selection using national registration data from the Japanese Hereditary Breast and Ovarian Cancer Syndrome Consortium., Results: Our study included 318 female patients. Among these patients, 23.7% of patients with BRCA1/2 mutations and 61.8% of patients without these variants underwent breast-conserving surgery (P < .01). Among the patients with BRCA1/2 mutations, those who chose breast-conserving surgery tended not to undergo risk-reducing salpingo-oophorectomy (P < .05). Among the patients with BRCA1/2 mutations who underwent mastectomy for the affected side, 31.8% received contralateral risk-reducing mastectomy. Patients diagnosed with breast cancer under the age of 50 years were more likely to have contralateral risk-reducing mastectomy than patients over the age 50 years (P < .05)., Conclusions: Patients with BRCA1/2 mutations tend to choose mastectomy. However, it is speculated that the final surgical method selection is made in consideration of not only the test results but also with careful consideration of the patient, taking into account other factors including individual values for risk-reducing surgeries and the age of breast cancer onset., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The present case is the first report in Japan in which a breast cancer was discovered as a result of prospective magnetic resonance imaging (MRI) screening study for BRCA1/2 mutation carriers who were free of breast or ovarian cancer. This case is significant and it verifies the importance of MRI screening in breast or ovarian cancer-free BRCA1/2 mutation carriers who do not exhibit positive mammographic or ultrasonographic findings.

It has been estimated that genetic factors or a combination of genetic and environmental factors play a role in the development of 10-15% of all cancers. A genetic cause of hereditary cancer has been identified in more than 40 diseases till now. For preventing this cancer, gene testing is essential because it has no definite clinical marker as in hereditary non-polyposis colorectal cancer: HNPCC. Much more experience must be accumulated in this testing at the clinical base in order to increase specificity and sensitivity while safeguarding ethical, legal and social issues (ELSI). Recently, the Personal Information Protection Law was enforced. Gene inspection involving hereditary cancer should be carried out under a comprehensive gene medical examination organization. It is important for the family doctor, medical specialist, and gene inspection person in charge to cooperate closely with one another, and this will be a subject of future study.

Substantial numbers of variants of unknown significance (VUSs) have been identified in BRCA1/2 through genetic testing, which poses a significant clinical challenge because the contribution of these VUSs to cancer predisposition has not yet been determined. Here, we report 10 Japanese patients from seven families with breast or ovarian cancer harboring the BRCA2 c.7847C>T (p.Ser2616Phe) variant that was interpreted as a VUS. This variant recurs only in families from Japan and has not been reported in the global general population databases. A Japanese patient with Fanconi anemia with compound heterozygous variants c.7847C>T (p.Ser2616Phe) and c.475+1G>A in BRCA2 was reported. In silico predictions and quantitative cosegregation analysis suggest a high probability of pathogenicity. The clinical features of the variant carriers were not specific to, but were consistent with, those of patients with hereditary breast and ovarian cancer. A validated functional assay, called the mixed‐all‐nominated‐in‐one‐BRCA (MANO‐B) method and the accurate BRCA companion diagnostic (ABCD) test, demonstrated the deleterious effects of the variant. Altogether, following the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines, this variant satisfied the "PS3," "PM2," "PM3," and "PP3" criteria. We thus conclude that the BRCA2 c.7847C>T (p.Ser2616Phe) variant is a "likely pathogenic" variant that is specifically observed in the Japanese population, leading to a breast and ovarian cancer predisposition. [ABSTRACT FROM AUTHOR]