Genetic Testing of Japanese Familial Breast Cancer Patients and Their Management

Abstract

Mutation analysis of BRCA1 and BRCA2 was conducted in 113 Japanese familial breast cancer （FBC） patients. Fifteen deleterious mutations （13.3%） were identified in BRCA1 and 21 deleterious mutations（18.6%） were identified in BRCA2. These findings demonstrate that the cumulative frequency of BRCA1 and BRCA2 mutations in Japanese breast cancer families（31.9%）is within the range observed in Caucasian breast cancer families. The mean age at the time of diagnosis of BRCA1-associated FBCs and that of BRCA2-associated FBCs（44 years for both）were significantly younger than that of the control group（54 years）and the incidence of bilateral tumors was significantly higher in the BRCA1-associated FBCs （32%）and BRCA2-associated FBCs（29%）than in the control group（6%）. BRCA1-associated FBCs showed a significant increase in histologic grade 3 tumors（p ＜ 0.01） and estrogen receptor negative tumors（p ＜ 0.01）. However, such characteristics were not observed in the BRCA2-associated FBCs. BRCA1-associated FBCs, but not BRCA2-associated FBCs, seem to have biologically aggressive phenotypes.