Contralateral breast cancer risk in BRCA1 and BRCA2 mutation carriers in a large cohort of unselected Chinese breast cancer patients

다국어 초록 (Multilingual Abstract)

To estimate the cumulative risk of contralateral breast cancer (CBC) in BRCA1/2 carriers in a large cohort of unselected Chinese breast cancer patients. Our study comprised 9,401 unselected Chinese breast cancer patients and BRCA1/2 germline mutations were determined in all patients. After a median follow‐up of 5.7 years, 181 patients developed CBC in this cohort. Compared to noncarriers, BRCA1 and BRCA2 carriers had a 4.52‐fold (95% CI, 2.63–7.76) and 5.54‐fold (95% CI, 3.51–8.74) increased risk of CBC, respectively. The 10‐year cumulative risk of CBC was 15.5% (95% CI, 9.9–24.2) for BRCA1 carriers, 17.5% (95% CI, 10.9–28.0) for BRCA2 carriers and 3.2% (95% CI, 2.5–4.1) for noncarriers. Younger age at first breast cancer diagnosis was significantly associated with an increased 10‐year risk of CBC for BRCA1 carriers (≤40 years vs. >40 years: 21.5% vs. 11.9%, unadjusted hazard ratio [HR] = 2.51, 95% CI, 1.03–6.15, p = 0.044), but not for BRCA2 carriers and noncarriers. The 10‐year cumulative CBC risk was significantly higher in both BRCA1 and BRCA2 carriers who had a family history of breast cancer than in those who did not (BRCA1: 27.5% vs. 9.4%, adjusted HR = 2.64, 95% CI, 1.01–6.97, p = 0.049; BRCA2: 27.1% vs. 12.8%, adjusted HR = 2.29, 95% CI, 1.04–5.06, p = 0.040). In conclusion, the risk of CBC was a substantial high in BRCA1/2 carriers in unselected Chinese breast cancer patients, and CBC risk is much more remarkable in both BRCA1 and BRCA2 carriers who had a family history of breast cancer. Younger age at first breast cancer diagnosis also enhanced CBC risk in BRCA1 carriers.
What's new?
While germline mutations in the BRCA 1 and BRCA2 genes raise contralateral breast cancer (CBC) risk in women, the influence of these mutations on CBC risk varies among ethnic populations. This study examined CBC risks in BRCA1/2 mutation carriers specifically in a cohort of unselected Chinese breast cancer patients. Cumulative CBC risk was significantly increased for BRCA1/2 mutation carriers, especially those with family history of the disease. Risks were lower relative to Caucasian and Jewish cohorts, possibly because, unlike previous analyses, the authors of the present study did not recruit BRCA1/2 mutation carriers based on family history of breast cancer.