Welcome to The Million Women Study

What is The Million Women Study? The Million Women Study started recruiting participants more than 20 years ago, in 1996. The initial stimulus was to obtain robust prospective information on the risk of breast cancer associated with use of different types of menopausal hormone therapy. When planning the necessary large-scale prospective study, an equally important aim was to obtain reliable information on the effects of other potentially modifiable factors that affect women’s health as they age.

Who is taking part in the study? The study includes 1 in 4 of all UK women born between 1935 and 1950, recruited through 66 NHS breast screening centres in England and Scotland in 1996-2001.

What is the Million Women Study investigating? While the initial stimulus was to study the risk of breast cancer and other conditions associated with the use of menopausal hormones, most of the women who joined the study had reached adulthood in the 1960s and had considerably different lifestyles to those of previous generations. For example, large proportions had begun smoking and using oral contraceptives as teenagers and young adults. The prevalence of obesity was also increasing and there were claims that other behaviours, such as diet, had important effects on health. To answer questions about the effects of these factors on health reliably requires large scale population-based evidence. The Million Women Study is therefore investigating the short-term and long-term effects of these and many other factors on women’s risk of developing or dying from different types of cancer, heart disease, stroke, dementia and other mental and neurodegenerative disorders, and many other conditions in middle and in old age.

Who is involved in conducting the study? The co-ordinating centre is based in the Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford. The study was set up in collaboration with the NHS Breast Screening Programme, and is now funded mainly by the UK Medical Research Council and Cancer Research UK. To find out the staff members, and breast screening centres involved in the Million Women Study please click here

Are Million Women Study data available for sharing? We want the Million Women Study data to be used as widely as possible for health-related research, and welcome applications for open-access sharing with researchers around the world. Information about the available baseline data may found at Data Dictionary for available questionnaire data, and outcome data at Available data and timeline for future data releases Applications may be made by filling in this form data access enquiry form

For further information please see our Cohort Profile