Welcome to The Million Women Study

What is The Million Women Study? The Million Women Study is a national study of women’s health, involving more than one million UK women aged 50 and over. It is a collaborative project between Cancer Research UK and the National Health Service, with additional funding from the Medical Research Council and the Health and Safety Executive, which aims to answer many outstanding questions about the factors affecting women’s health in this age group. The main focus of the study relates to the effects of hormone replacement therapy use, but the large size of the study means that a very broad range of health issues can be addressed.

What is the Million Women Study investigating? The Million Women Study is investigating how various reproductive and lifestyle factors affect women’s health. In particular, the study is looking at how hormone replacement therapy affects a woman’s breasts and other aspects of her health. Other factors being investigated include diet, exercise, employment patterns, oral contraceptive use, childbirth and breastfeeding, and family history of illness, in relation to a wide range of cancers and to other conditions such as heart disease, stroke, dementia, mental health and fractures.

Who is taking part in the study? Between 1996 and 2001, women were invited to join the Million Women Study when they received their invitation to attend breast screening at one of 66 participating NHS Breast Screening Centres in the UK. At these centres, women received a study questionnaire with their invitation, which they were asked to complete and return at the time of screening. Around 70% of those attending the programme returned questionnaires and agreed to take part in the study – this excellent response means that over 1 in 4 women in the UK in the target age group are now participating in the study. It also means that the Million Women Study is the largest study of its kind in the world.

Who is involved in conducting the study? The Million Women Study is a nationwide study coordinated by experienced researchers based in Oxford. The study is supported by public funds from Cancer Research UK, the Medical Research Council and the Health and Safety Executive. Our Privacy Notice can be accessed here. To find out the staff members, and breast screening centres involved in the Million Women Study, visit the staff page