Hormone replacement therapy (HRT) may not increase the risk of breast cancer among BRCA1-positive women who undergo preventative oophorectomy, according to a study published in JAMA Oncology.1
For this prospective study, researchers evaluated the outcomes of 872 BRCA1carriers without any personal history of cancer who underwent preventative bilateral oophorectomy. Participants completed a questionnaire detailing HRT use at baseline and every 2 years thereafter.
Of the 872 patients, 495 (57%) women chose not to use HRT therapy; 377 (43%) patients did. Among HRT users, 259 (69%) took estrogen alone, 66 (18%) used estrogen plus progesterone, 40 (11%) used progesterone alone, and 80 (21%) used another formulation.
Ninety-two (10.6%) cases of breast cancer were reported during the mean follow-up period of 7.6 years. The use of any HRT post-oophorectomy was not, however, associated with an increase in breast cancer risk (hazard ratio [HR], 0.97; 95% CI, 0.62-1.52; P= .89).
Researchers did find that after 10-years, the cumulative incidence of breast cancer was 22% among women who used estrogen plus progesterone vs 12% among patients who used estrogen only (absolute difference, 10%; P= .04). It was suggested that estrogen alone may have a protective effect, decreasing the risk of breast cancer by 8% with every year of use.
The authors concluded that “these findings suggest that use of estrogen after oophorectomy does not increase the risk of breast cancer among women with a BRCA1 mutation and should reassure BRCA1 mutation carriers considering preventive surgery that HRT is safe. The possible adverse effect of progesterone-containing HRT warrants further study.”
- Kotsopoulos J, Gronwald J, Karlan BY, et al. Hormone replacement therapy after oophorectomy and breast cancer risk among BRCA1mutation carriers. JAMA Oncol. 2018 Apr 19. doi: 10.1001/jamaoncol.2018.0211 [Epub ahead of print]