Background: The purpose of this investigation was to elucidate the clinicopathologic characteristics of BRCA1- and BRCA2-associated hereditary breast carcinomas (HBCs) in Japanese women.
Methods: Various clinicopathologic characteristics of HBCs arising in patients with BRCA1 or BRCA2 germline mutations were compared with those of the control group (sporadic breast carcinomas).
Results: The mean age at the time of diagnosis of BRCA1-associated HBCs and that of BRCA2-associated HBCs (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 HBCs (32%) and BRCA2-associated HBCs (29%) than in the control group (6%). BRCA1-associated HBCs showed a tendency (P = 0.06) toward an increase in solid-tubular type tumors and a significant increase in histologic grade 3 tumors (P < 0.01) and lymphatic invasion positive tumors (P < 0.05) compared with the control group. BRCA1-associated HBCs were significantly more estrogen receptor negative (P < 0.01), c-erb B-2 negative (P < 0.05), and p53 positive (P < 0.01), and they also showed a significant increase in MIB-1 staining grades (P < 0.01) as well as microvessel counts (P < 0.05) compared with the control group. However, there was no significant difference in these parameters between the BRCA2-associated HBCs and the control group.
Conclusions: BRCA1-associated HBCs in Japanese women have biologically aggressive phenotypes. However, BRCA2-associated HBCs are without distinctive clinicopathologic features compared with sporadic breast carcinomas.