Some HRT Reduces Breast Cancer Risks

Estrogen only HRT appears to protect against breast cancer for hysterectomy

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) What's a girl to do when the flow stops and menopause rages? Is she to take hormone replacement therapy (HRT), or avoid it all costs because everyone knows it causes breast cancer - right? Not so fast there, lady.

Researchers have added a new wrinkle to the HRT debate here of late. A new study shows that estrogen-only HRT appears to protect against developing or dying from breast cancer in women who have had a hysterectomy, and this benefit lasts for years - even after the treatment has stopped.

"Have a long, slow conversation with your gynecologist about HRT."

The Women's Health Initiative (WHI) involving nearly 11,000 women began in 1993 to evaluate what, if any, impact conjugated equine estrogen had on chronic disease. 

The women were between the ages of 50 and 79 and they had all had hysterectomies. In the randomized trial, the ladies were given either estrogen or a placebo for nearly seven years. The study was abruptly halted a year early in 2004 because of an increased risk of blood clots and stroke.

In a follow-up study, researchers have found that compared to women who have never taken HRT, study participants who took the estrogen for about six years were more than 20 percent less likely to develop breast cancer. These women also had a significantly lower risk of dying from the disease for nearly five years after stopping the treatment.

Study leader, Garnet Anderson, Ph.D. from the Fred Hutchinson Cancer Research Center, said, "These latest results should provide reassurance about breast safety of estrogen use for durations of about 5 years for women with a hysterectomy seeking relief from postmenopausal symptoms."

Women who have not had hysterectomies aren't usually prescribed estrogen-only therapy because of the risks of uterine cancer.

The new study followed 7,645 of the original WHI participants from March 2005 to August 2009 - roughly five years after stopping the HRT. 

Compared to women who received a placebo during the study, researchers found the women who received the estrogen experienced:

  • A 23 percent reduction in the incidence of invasive breast cancer during a nearly 12-year follow-up period
  • Of the treated women who did develop breast cancer, there was a 63 percent reduction in the deaths from the disease.

These findings related only to women who had no personal history of benign breast disease or a strong family history of breast cancer.

The authors caution that estrogen therapy should not be used for the sole purpose of reducing breast cancer risk "in light of the lack of benefit noted in populations at higher risk (including those with a strong family history of breast cancer or benign breast disease) and the additional risk of stroke and blood clots."

This analysis was published March 6, 2012 Online First in The Lancet Oncology

Reviewed by: 
Review Date: 
March 6, 2012
Last Updated:
March 6, 2012