Breast cancer risk associated with BRCA1 and BRCA2 pathogenic variants in the Eastern Chinese population

Background

Population-based penetrance studies of breast cancer gene 1/2 (BRCA1/2) pathogenic or likely pathogenic (P/LP) variants in the Eastern Chinese population are currently lacking; thus, we aimed to investigate the penetrance of breast cancer and other malignant tumors among BRCA1/2 P/LP variant carriers using a population-based breast cancer cohort from communities in Eastern China.

Methods

Between July 2019 and March 2021, we tested 2216 breast cancer probands from Chinese communities for BRCA1/2 mutations and collected detailed information on the age, survival status, and malignancy history of first-degree relatives. The kin-cohort method was used to calculate the penetrance of breast cancer and other malignant tumors.

Results

Of the 2216 breast cancer probands, 109 (4.90%) carried BRCA1/2 P/LP variants, 49 in the BRCA1 gene and 60 in the BRCA2 gene. The penetrance of female breast cancer by 85 years of age was 22.50% and 18.20% in BRCA1 and BRCA2 P/LP variant carriers, respectively. The penetrance of ovarian cancer by 85 years of age was 26.00% in BRCA1 P/LP variant carriers. The penetrance of other malignancies did not reach statistical significance owing to the small number of events.

Conclusions

Our findings showed that breast cancer penetrance among BRCA1 and BRCA2 P/LP variant carriers was 22.50% and 18.20%, respectively, which suggests that prophylactic mastectomy may not be necessary for such Chinese individuals.

Trial registration

ClinicalTrials.gov; https://clinicaltrials.gov/ct2/show/NCT04265937.