Oxford researchers have recruited their millionth volunteer for the UK's largest study into female health.

The figure means that one in four women aged 50 to 64 are taking part in the Million Women Study, which was launched three years ago.

As a result, the Imperial Cancer Research Fund scientists based at the Radcliffe Infirmary hope major questions about women's health could soon be answered. Prof Valerie Beral said: "When we started the Million Women Study many though it was far too ambitious.

"Thanks to the enthusiasm of women throughout the country, it will now be possible to answer many important questions surrounding hormone replacement therapy and women's health."

The main aim is to look at HRT and its links with breast cancer.