The breast and ovarian cancer risks in Korea due to inherited mutations in BRCA1 and BRCA2: A preliminary report

Purpose: To estimate the cumulative risk till each age (penetrance) of breast and ovarian cancers among female family members with BRCA1 and BRCA2 mutation. Methods: Among the 61 BRCA1 mutation carriers in the 42 families and 47 BRCA2 mutation carriers in 31 families identified at 5 academic breast clinics, the probands were excluded to estimate the cumulative risk till each age of breast cancer in the Korean BRCA1 and BRCA2 carriers. Using Kaplan-Meier analyses, cumulative cancer risk estimates were determined. Results: By the age 70, the female breast cancer risk for the BRCA1 and BRCA2 mutation carriers was 72.1% (95% confidence interval [CI]=59.5% to 84.8%) and 66.3% (95% CI=41.2% to 91.5%), respectively, and the ovarian cancer risk was 24.6% (95% CI=0% to 50.3%) and 11.1% (95% CI=0% to 31.6%), respectively. The contralateral breast cancer risk at 5 years after primary breast cancer was estimated as 16.2% (95% CI=9.3% to 23.1%) for the 52 breast cancer patients with the BRCA1 mutation and 17.3% (95% CI=9.7% to 24.0%) for the 35 breast cancer patients with the BRCA2 mutation. Conclusion: The penetrance of BRCA mutations in Korea is largely consistent with the previous studies on Western populations. However, the small number of the cases, the high proportions of probands in the study subjects, the short term follow-up, and large confidence intervals are the limitations of the current study. The Korean Hereditary Breast Cancer Study (KOHBRA Study) may definitely answer this question.