April 19, 2018
1 min read

Estrogen after oophorectomy does not increase breast cancer risk

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The use of estrogen following preventive oophorectomy did not appear to increase the risk for breast cancer among women carrying a BRCA1 mutation, according to findings published in JAMA Oncology.

These findings should reassure women with BRCA1 mutations who are considering preventive surgery that hormone replacement therapy is safe.

“In North America, most [women with inherited BRCA1 mutations] will undergo prophylactic oophorectomy to prevent ovarian cancer; many will experience early surgical menopause and possibly long-term health consequences associated with abrupt ovarian hormonal withdrawal,” Joanne Kotsopoulos, PhD, associate professor at Dalla Lana School of Public Health at University of Toronto and scientist at Women's College Research Institute of Women’s College Hospital, and colleagues wrote. “Exogenous hormone use may be prescribed to mitigate adverse effects associated with oophorectomy. Although hormone replacement therapy after surgical menopause is prescribed to BRCA1 mutation carriers without a personal history of breast cancer, the impact on breast cancer risk remains unclear.”

The researchers conducted a prospective longitudinal cohort study of 872 BRCA1 carriers (mean age, 43.4 years) recruited from 80 centers in 17 countries. All participants underwent genetic testing for a BRCA1 or BRCA2 mutation in response to a family history of ovarian or breast cancer.

Patients completed questionnaires every 2 years on use of hormone replacement therapy.

Mean follow-up was 7.6 years.

Ninety-two (10.6%) breast cancer diagnoses occurred during the study.

There was no association between hormone replacement therapy and breast cancer (HR = 0.97; 95% CI, 0.62-1.52).

The researchers noted a difference between the effects of estrogen alone and combination hormonal therapy.

The cumulative incidence of breast cancer was 22% at 10 years of follow-up among women who used estrogen plus progesterone compared with 12% among women who used estrogen alone (absolute difference, 10%; log rank P = .04).

“Our findings indicate the BRCA1 mutation carriers should not avoid risk-reducing surgery because of the fear associated with estrogen-alone hormone replacement therapy use,” the researchers wrote. “The potential harmful effect of progesterone-containing hormone replacement therapy is of interest, especially given the evidence implicating the progesterone/RANK pathway in the etiology of BRCA1 breast cancer. However, future studies are necessary to confirm our findings.” – by Andy Polhamus

Disclosures: The authors report no relevant financial disclosures.