Abstract:      Background and purpose: BRCA1 and BRCA2 mutation carriers have a high lifetime risk of developing breast and ovarian cancer. Through genetic counseling, mutation carriers can take the appropriate measures to reduce such cancer risk. At present, almost all related studies were conducted in Caucasian, while, the studies in Chinese population were rare. This study aimed to investigate the risk of breast cancer in BRCA1 and BRCA2 mutation carriers in Chinese Han population. Methods: Twenty unrelated families with BRCA1 or BRCA2 mutations were reviewed. Kaplan-Meier analyses were used to estimate the cumulative risks of unilateral breast cancer and contralateral breast cancer for female BRCA1 and BRCA2 mutation carriers. Results: Breast cancer risk to 70 years (penetrance) was 67.2% (sx 0.100) for BRCA1 and 76.8% (sx 0.079) for BRCA2, respectively. Different from BRCA1 mutation carriers, the cumulative incidence of breast cancer in BRCA2 mutation carriers remained increasing after 70 years, reaching 93.1% at age 80. The 10- and 20-year risk for contralateral breast cancer was 19.4% (sx 0.089) and 50.3% (sx 0.155) for BRCA1/2 mutation carriers. Conclusion: BRCA1 and BRCA2 mutation carriers in Chinese Han population have a high risk of developing breast cancer. Thus, it has great clinical significance to test mutations in BRCA1/2 genes in Chinese
high-risk population.

Key words:  BRCA1, BRCA2, Breast cancer, Penetrance