Hormone replacement therapy may in fact be safe for women who carry the breast cancer gene mutation, says new Canadian research, which questions a commonly held belief that it can further increase the risk of developing the disease.
Researchers at Women's College Hospital analyzed data from 472 women, all of whom carried the BRCA1 gene mutation. They found that taking hormone replacement therapy was linked with a 42 per cent reduction in the risk of developing breast cancer.
Women who carry the BRCA1 mutation are between three and seven times more likely to develop breast cancer than women without the mutation.
Many women take hormone replacement therapy (HRT) after menopause to reduce the severity of symptoms, which can include hot flashes, dry skin, decreased libido and irritability.
Carriers of the BRCA1 mutation often opt to lower their breast cancer risk by having their ovaries removed. The procedure, known as oophorectomy, induces menopause.
Some studies have linked HRT with a slight increase in risk of developing both breast and ovarian cancer.
However, the potential health effects of HRT in women who carry the BRCA1 gene is still unclear.
"The magnitude of the association appeared to be as great, or even greater, for women after surgical menopause than it was for women after natural menopause," the study's authors wrote. "This information should be reassuring to women who wish to undergo preventive oophorectomy before menopause, but it needs to be confirmed in subsequent studies."
The research was led by Dr. Steven Narod. The study's findings are published in the Journal of the National Cancer Institute.
An accompanying editorial cautioned that while other observational studies have not found a link between hormone therapy and an increased risk of breast cancer in gene carriers, subsequent clinical trials have found hormone therapy increases the risk of recurrence in breast cancer survivors.
"The results presented by [Narod and colleagues] regarding hormone therapy use in postmenopausal BRCA1 mutation carriers provide some evidence for safety but are insufficient to reliably inform routine clinical practice," wrote Dr. Rowan Chlebowski of the Los Angeles Biomedical Research Institute and Ross Prentice of Seattle's Fred Hutchinson Cancer Research Center.
"As a result, continued caution in prescribing hormone therapy to women with BRCA1 mutations who are at high risk for breast cancers remains prudent."
