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Hormone Replacement Therapy Not Linked to Breast Cancer Recurrence, Study Finds

Hormone therapy can be an effective treatment for symptoms that affect the genitals and urinary tract in female cancer patients, but researchers still note that certain types of therapies may still raise cancer risks despite latest findings.

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Hormone replacement therapy (HRT) can be an effective treatment, but some types of HRT have been associated with a higher risk of breast cancer recurrence.Cris Canton/Getty Images

Breast cancer survivors often experience symptoms of declining estrogen levels, including hot flashes, night sweats, vaginal dryness, and urinary tract infections. While hormone replacement therapy (HRT) can be an effective treatment for these adverse effects, some types of HRT have been associated with a higher risk of breast cancer recurrence, according to BreastCancer.org.

The American Cancer Society warns that higher estrogen levels may heighten the risk of breast cancer growth, and doctors may caution women with a history of breast cancer to not take types of systemic HRT that affect the entire body. HRT has also been linked to cardiovascular risks, such as heart disease, stroke, and blood clots.

A study published this month in the Journal of the National Cancer Institute, however, found that menopausal hormone therapy for breast cancer survivors is not associated with breast cancer reoccurrence.

Scientists in Denmark analyzed data from the country’s national prescription registry regarding postmenopausal women diagnosed between 1997 and 2004 with early-stage breast cancer who received no treatment or five years of hormone therapy. Among 8,461 women who had not received vaginal estrogen therapy or menopausal hormone therapy before a breast cancer diagnosis, 1,957 and 133 used vaginal estrogen therapy or menopausal hormone therapy, respectively, after diagnosis.

In accordance with national treatment guidelines during the study period, all patients were allocated either to five years of tamoxifen (one of the most widely used breast cancer treatments) or an aromatase inhibitor (which lowers estrogen levels by stopping an enzyme in fat tissue), or both treatments in sequence.

The researchers observed no higher odds for cancer returning or death in those who had the therapy compared with those who didn’t.

“These results suggest that breast cancer survivors on tamoxifen with severe symptoms [of genitals and urinary tract] can take vaginal estrogen therapy without experiencing an increase in their risk for breast cancer recurrence,” said Elizabeth Cathcart-Rake, MD, who wrote in an accompanying editorial to the investigation.

Study authors noted, however, that a subgroup analysis revealed an increased risk of recurrence, but not death, in patients receiving vaginal estrogen therapy with aromatase inhibitors.

“Patients who are taking aromatase inhibitors should try alternative strategies for management of genitourinary symptoms because vaginal estrogen therapy will likely increase their risk for breast cancer recurrence,” said Dr. Cathcart-Rake, who is a physician at the Mayo Clinic in Rochester, Minnesota.

Overall, Cathcart-Rake sees the investigation helping to clarify the potential safety and hazards of taking such treatments. “This large cohort study helps to inform the nuanced discussions between clinicians and breast cancer survivors about the safety of vaginal estrogen therapy,” she said.

BreastCancer.org recommends that because the risks and benefits are different for every woman, breast cancer patients should educate themselves and talk to their doctor to decide if HRT is right for them.