Cancer Epidemiology Unit

You are here: HomeResearch

Million Women Study

The Million Women Study is a cohort study involving 1.3 million women in the UK, funded by Cancer Research UK and the Medical Research Council, and run in collaboration with the National Health Service Breast Screening Programme. Its main aim is to investigate the effect of hormone replacement therapy (HRT) on women’s health.

The Million Women Study was officially launched in 1997 and with the help of over 60 NHS breast screening centres around the UK, has recruited 1.3 million women over the age of 50. The main focus of the study is on the effects of hormone replacement therapy (HRT) use and the risk of breast cancer, but the large size of the study means that a very broad range of health issues can be addressed. Million Women Study findings, together with results from other recent studies, have influenced UK national prescribing guidelines for HRT.

Major publications include the first paper on breast cancer and HRT in the Million Women Study, published in August 2003, and subsequent reports on fractures (2003), breast screening (2004), endometrial cancer (2005), ovarian cancer (2007), and on cancer risk associated with obesity (2007) and with moderate alcohol intake (2009).

Full details of the Million Women Study are available on the website