Prevalence of BRCA1 and BRCA2 mutations in Japanese patients with triple-negative breast cancer: A single institute retrospective study

Numerous databases for risk assessment of BRCA1/2 gene mutations contain insufficient data about Asians. Furthermore, few studies have reported the prevalence of germline BRCA1/2 mutations in Japanese patients, particularly those with triple-negative breast cancer (TNBC). The present study was a retrospective analysis of data from patients with TNBC who underwent BRCA1/2 mutation testing at Osaka International Cancer Institute (Osaka, Japan) between October 2014 and March 2020. A total of 65 patients with TNBC underwent a test for BRCA1/2 mutations, and 13 (20.0%) had deleterious mutations in the BRCA1 or BRCA2 genes. Furthermore, 12 out of 29 patients with a family history of breast or ovarian cancer had deleterious BRCA1/2 mutations, and only 1 of 34 without a family history had a mutation (41.4 vs. 2.9%; P=0.014). No patients aged >60 years had BRCA1/2 mutations; however, the age of diagnosis was not a significant risk factor for BRCA1/2 mutations (P=0.60). The prevalence of BRCA1/2 mutations in the present cohort of Japanese patients with TNBC was slightly higher than those reported in other larger studies from Europe and North America. Further data from large prospective studies are required to more precisely define the prevalence of BRCA1/2 mutations.