Hormone replacement therapy after menopause and risk of breast cancer in BRCA1 mutation carriers: a case–control study

Many BRCA1 mutation carriers undergo elective surgical oophorectomy (often before menopause) to manage their elevated risk of developing ovarian cancer. It is important to clarify whether or not the use of hormone replacement therapy (HRT) to mitigate the symptoms associated with surgical or natural menopause is safe in women with an inherited BRCA1 mutation and no personal history of breast or ovarian cancer. We conducted a case–control analysis of 432 matched pairs of women with a BRCA1 mutation. Detailed information on HRT use after menopause (duration, type, age at first/last use, formulation) was obtained from a research questionnaire administered at the time of study enrollment. Conditional logistic regression was used to estimate the odds ratio (OR) and 95 % confidence intervals (CI) associated with HRT use. The mean duration of HRT use after menopause was 4.3 years among the cases and 4.4 years among the controls (P = 0.83). The adjusted OR for breast cancer comparing all women who ever used HRT to those who never used HRT was 0.80 (95 % CI 0.55–1.16; P = 0.24). Findings did not differ by type of menopause (natural vs. surgical), by recency of use, by duration of use, and by formulation type. These findings suggest that a short course of HRT should not be contra-indicated for BRCA1 mutation carriers who have undergone menopause and who have no personal history of cancer.