Hormone-Replacement Therapy Is Not Associated With Increased Risk for Death in Patients With Breast Cancer, New Study Results Show

Hormone-replacement therapy may help alleviate symptoms in women with breast cancer, though many clinicians report being apprehensive about administering these treatments due to fear of cancer recurrence.

However, recent study results found that the risk between hormone-replacement therapy — such as vaginal estrogen therapy or menopausal hormone therapy — and breast cancer recurrence may be more nuanced than previously thought.

“The rationale for (these therapies causing) recurrence is that the systemic hormones trigger (dormant) cancer cells,” study author Dr. Soren Cold, from the Department of Oncology at Odense University Hospital in Denmark, said in an interview with CURE®.

Two clinical trials conducted in the 1990s showed that women who underwent menopausal hormone therapy were more likely to experience breast cancer recurrence. However, these studies had small sample sizes and short follow-up periods.

Hormone-replacement therapy has been used to relieve menopausal symptoms including hot flashes, night sweats, mood swings, vaginal dryness and decreased sex drive — all of which may occur in women who are undergoing breast cancer treatment.

In this particular study, researchers analyzed data from 8,461 postmenopausal women who were diagnosed with early-stage breast cancer between 1997 and 2004. None of these women received hormone therapy before receiving a breast cancer diagnosis. After diagnosis, 1,957 used vaginal estrogen therapy, while 133 used menopausal hormone therapy.

Patients who were older, had large tumors and/or had cancer in their lymph nodes were less likely to use hormone therapy.

Findings showed that the use of vaginal estrogen therapy was associated with an increased risk of breast cancer recurrence for postmenopausal patients who were treated with post-surgical aromatase inhibitors.

However, neither vaginal estrogen therapy nor menopausal hormone therapy were associated with an increased risk of death from breast cancer, according to study findings, which analyzed mortality data for an average of more than 15 years.

“Therefore, we urge researchers to assess in future studies whether there is an increased mortality associated with (vaginal endocrine therapy) use in breast cancer survivors, particularly in patients treated with (aromatase inhibitors),” the study authors wrote.

The researchers also noted that there was no evidence of an increased recurrence risk for patients who were treated with tamoxifen or for those who did not receive post-surgical endocrine therapy.

“For women on tamoxifen or no adjuvant endocrine therapy, we could not identify a risk with the use of vaginal estrogens,” Cold said. “For women on aromatase inhibitors, the modest increased risk of recurrence should be taken into account opposite the positive effect of relieving local symptoms.”

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