HRT and breast cancer mortality

The first publication of breast cancer mortality data from the Women’s Health Initiative (WHI) trial shows a small but significant increase in deaths among women using combined oestrogen plus progestin HRT.

A paper based on WHI trial data shows a small but significant increase in deaths among women using combined oestrogen plus progestin HRT.

This is in keeping with the known small increase in breast cancer cases in this group of women after five years of use. The increase does not apply to women taking oestrogen-only HRT.

The use of lowest effective dose of HRT for women at the time of menopause in women who have significant symptoms is still the most effective treatment recommended for those women who are healthy and take it for a limited time.

 AMS Executive

Link to the free abstract:

Estrogen Plus Progestin and Breast Cancer Incidence and Mortality in Postmenopausal Women
JAMA. 2010;304(15):1684-1692. doi:10.1001/jama.2010.1500

Professor Martha Hickey MBChB MD FRANZCOG comments on the paper for AMS:

Previous data from this large (>16,000) randomised controlled trial has shown that women using oral continuous combined HRT were more likely to develop breast cancer after 5 years of use, and that these cancers were, on average, larger and more likely to be node-positive.

These newly reported follow-up data after an average of 11 years shows there were more deaths directly attributed to breast cancer (25 deaths vs. 12 deaths; HR 1.96; 95% CI, 1.00-4.04; P = .049) as well as more deaths from all causes occurring after a breast cancer diagnosis among women who received oestrogen plus progestin compared with women in the placebo group.

This amounts to a risk of death from breast cancer of 1.3 in every 10,000 women per year taking placebo and a risk of 2.6 in every 10,000 women taking combined HRT (approximately one extra death per year).

These data differ from that previously seen in observational studies where breast cancers in HRT users appeared to show better prognostic factors than those seen in non-HRT users. (Chlebowski 2010).

The North American Menopause Society has issued a statement in response to this publication likening the increased risk of breast cancer with combined HRT to that of 5 years’ delay in menopause, late menopause being a known risk factor for breast cancer.

AMS recognises the importance of these new findings. They provide more information for women with moderate to severe menopausal symptoms who may be considering using HRT to treat these symptoms. The increased risk of breast cancer and breast cancer deaths attributable to HRT was small in this study, but should be considered by the woman and her health care provider in making an individualised choice of the risks and benefits of HRT use.

For more comments on the mortality data, see:
The North American Menopause Society media statement

Content updated 8 November 2010