Breast cancer rates among women in their 50s are down. So, too, are prescriptions for hormone replacement therapy. So, could there be a connection?

Summary

Hormone replacement therapy is far less popular than it was. And, according to data gathered by Cancer Research UK, breast cancer rates are also down. The parallel is striking, although it does not prove HRT actually causes breast cancer. It will be interesting to see if the trend continues in years to come.

Introduction

One of the main factors influencing the uptake of hormone replacement therapy (HRT) to treat menopausal symptoms is the discovery that it may increase the risk of breast cancer. This finding emerged from the Women's Health Initiative in the USA and the Million Women Study in the UK. Therefore, women have begun to turn away from HRT. A new study from the leading charity Cancer Research UK now examines the link between HRT uptake and subsequent breast cancer rates.

What was done

Professor Max Parkin of Queen Mary College, London, a Cancer Research UK statistician, looked at breast cancer rates among women aged between 50 and 54 and between 55 and 59. He also checked the numbers receiving prescriptions for HRT.

What was found

In 2000, more than 40 percent of women aged 50 to 54 were on HRT and more than 35 percent of the 55-59 age group. By 2006, HRT users between 50 to 54 had fallen to 20 percent and to 15 percent in the 55 to 59 age group. Breast cancer rates in 1999 were 289 cases per 100,000 women and had fallen to 264 cases by 2005. Corresponding figures for those in the 55 to 59 age group were 304 cases in 1999 and 287 in 2005. However, among women in their sixties, breast cancer rates have actually been going up - which may be because of increased screening.

What this study means

The study does not show that HRT causes breast cancer. But one might well expect rates of breast cancer to fall in this way if HRT is a risk factor and it is then abandoned. Trends need to be followed long-term to clarify the link between HRT and breast cancer. In the meantime, Cancer Research UK says women should only take HRT for medical reasons and for as short a time as possible.

Source

Parkin M Is the recent fall in incidence of post-menopausal breast cancer in UK related to changes in use of hormone replacement therapy?European Journal of Cancer online February 12 2009 DOI: 10.1016/j.ejca.2009.01.016