Strong associations with CBC were found for carrying a BRCA1 (RR = 3.7; 95%CI:2.8-4.9), BRCA2 (RR = 2.8; 95%CI:1.8-4.3) or CHEK2 c.1100delC (RR = 2.7; 95%CI:2.0-3.7) mutation.
Thus, we conducted a prospective study of the relationship between oophorectomy and the risk of contralateral breast cancer in 1781 BRCA1 and 503 BRCA2 mutation carriers with breast cancer.
There were no significant differences in disease-free survival, overall survival, or breast cancer-specific survival (p = 0.799, 0.092, and 0.124, respectively) between BRCA 1/2 carriers and non-carriers, although BRCA 1/2 carriers showed significantly worse contralateral breast cancer-free survival (p < 0.0001) than non-carriers.
In the multivariable model, BRCA1/2 germline mutation status, family history, and systemic adjuvant treatment showed the strongest associations with CBC risk.
Purpose The Women's Environmental Cancer and Radiation Epidemiology (WECARE) study demonstrated the importance of breast cancer family history on contralateral breast cancer (CBC) risk, even for noncarriers of deleterious BRCA1/2 mutations.
Notably, women with ER-/PR- first tumors were more likely to develop CBC with the ER-/PR- phenotype (RR = 5.4, 95% CI 3.0-9.5), and risk remained elevated in multiple subgroups: BRCA1/2 mutation non-carriers, women younger than 45 years of age, women without a breast cancer family history, and women who were not treated with tamoxifen.
Contralateral prophylactic mastectomy (CPM) reduces the risk of contralateral breast cancer (BC) following unilateral BC, but may not increase survival in BRCA1/2 mutation negative women.
For contralateral breast cancer, the cumulative risk 20 years after breast cancer diagnosis was 40% (95% CI, 35%-45%) for BRCA1 and 26% (95% CI, 20%-33%) for BRCA2 carriers (hazard ratio [HR] for comparing BRCA2 vs BRCA1, 0.62; 95% CI, 0.47-0.82; P=.001 for difference).
Women diagnosed with breast cancer who carry pathogenic variants in genes with proven associations with breast cancer (BRCA1/2) or highly likely associations (PTEN, PALB2) require additional risk assessment to facilitate treatment decisions that will limit in-breast tumor recurrence and contralateral breast cancer.
Adjuvant radiotherapy for primary breast cancer in BRCA1 and BRCA2 mutation carriers and risk of contralateral breast cancer with special attention to patients irradiated at younger age.
The average cumulative risks by age 70 years for BRCA1 carriers were estimated to be 60% (95% confidence interval [CI] = 44% to 75%) for breast cancer, 59% (95% CI = 43% to 76%) for ovarian cancer, and 83% (95% CI = 69% to 94%) for contralateral breast cancer.
Contralateral breast cancer risk in BRCA1/2-positive families needs to be adjusted for phenocopy rates particularly in second-degree untested relatives.
We examined whether the risk of CBC associated with radiation treatment was higher among women with germline BRCA1/BRCA2 mutations than among non-carriers.
BRCA1 or BRCA2 mutation carriers more accurately perceived their risk for contralateral breast cancer, whereas women without a known mutation substantially overestimated this risk.