Hormone Replacement Therapy After Oophorectomy Is Not Shown to Increase Risk of Breast Cancer in BRCA1 Mutation Carriers

(May 4, 2018) JAMA Oncology recently published a study that looked at the risk of breast cancer in BRCA1 carriers who underwent a prophylactic bilateral salpingo-oophorectomy, a surgery that removes both ovaries before any sign of disease, followed by hormone replacement therapy (HRT). Eight hundred and seventy two women were followed for around 7.5 years after their surgery and 92 of them, or 10.6%, were diagnosed with breast cancer. Therefore, HRT was not associated with an increased risk of breast cancer.

However, the incidence of breast cancer between those who underwent estrogen-alone HRT and those who used estrogen plus progesterone HRT were different. After being followed for 10 years, the incidence of breast cancer for estrogen-alone HRT patients was 12%, whereas the incidence for those who had estrogen plus progesterone HRT was 22 percent. Therefore, the study concludes that, although BRCA1 mutation carriers don’t have an increased risk of breast cancer using estrogen-alone HRT after a prophylactic oophorectomy, further study is needed for HRT containing progesterone.