Pendulum of Hormone Replacement Therapy and Breast Cancer

Breast cancer incidence and mortality likely higher in women who use hormone replacement therapy

(RxWiki News) You’ve no doubt heard that hormone replacement therapy (HRT) used for menopause symptoms increases breast cancer risks. More recent studies have found that maybe HRT is okay. Now the pendulum has swung back.  

Women who use estrogen plus progestin hormone therapy are at higher risk of developing breast cancer, according to yet another study looking into the question.

Authors of this study also concluded that the likelihood of dying from breast cancer may be higher in hormone therapy users.

"Talk with your doctor when deciding about hormone therapy."

The mammoth Women’s Health Initiative (WHI) was the first study to find that combined hormone therapy increased a woman’s breast cancer risks. Observational studies completed more recently have found estrogen plus progestin were not linked to breast cancer.

To look at the question again, Rowan T. Chlebowski, MD, PhD, of Los Angeles Biomedical Research Institute (LA BioMed), and colleagues looked at 41,449 postmenopausal women from the WHI who had not had a hysterectomy.

All the women had had clean mammograms within two years. A total of 25,328 of the study participants used estrogen and progestin combined therapy, and 16,121 did not use any hormone therapy.

After a mean follow-up of 11.3 years, 2,236 women were diagnosed with invasive breast cancers.

Incidence was higher in hormone therapy users than nonusers – 0.60 vs. 0.42 – per year.

Breast cancer risks were highest in women who started taking hormone therapy at the start of menopause, with the risk declining as the years passed.

"Because survival after breast cancer diagnosis did not differ between estrogen plus progestin users and nonusers, the higher breast cancer incidence of those using estrogen plus progestin may lead to increased breast cancer mortality on a population basis," the authors write.

Adam Brufsky, MD, PhD, professor of medicine at the University of Pittsburgh School of Medicine, told dailyRx News, “These new results add to our concerns that prolonged HRT [hormone replacement therapy] may result in an increased risk of breast cancer.”

Additional research is needed to look at the question of hormone therapy and breast cancer, the authors suggested.

Dr. Chlebowski said in a statement, “As always, women should consult with their physicians and consider the potential risks of any hormonal therapy to help relieve the symptoms of menopause."

Findings from this study were released March 29 by the Journal of the National Cancer Institute. Funding and conflict of interest information was not provided.

Review Date: 
March 29, 2013