Genetic anticipation of familial breast cancer with or without BRCA mutation in the Korean population.

We investigated genetic anticipation of breast or ovarian cancer in patients with familial breast cancer. Among 201 patients with breast cancer who had a family history of breast or ovarian cancer, 95 families had affected familial members in the previous generation. Of these families, 2 were excluded because of insufficient data. From the 93 eligible families, 112 and 111 members were identified in the previous and proband generations, respectively. BRCA mutations were detected in 26 (28.0%) of the 93 probands. The median age at diagnosis of the first generation was 57 years and of the second generation was 40 years, which was a significant difference. The result from the mixed-effects model also demonstrated significant genetic anticipation (P < 0.0001). The expected age difference at onset of breast or ovarian cancer between the two generations was 17.06 years. BRCA mutation status did not influence the generational difference in age at diagnosis (17.99 vs. 16.62 y, P = 0.3973). Genetic counseling and early screening should be provided to women whose parent had a breast or ovarian cancer diagnosis.