Newsletter - January 2004
First Million Women Study results on breast cancer and hormone replacement therapy published
Follow-up of over 1 million women in the Million Women Study has confirmed findings from other recent studies that women currently using hormone replacement therapy (HRT) are more likely to develop breast cancer than those not using HRT. Past users are not at an increased risk. In the first paper on breast cancer and the effects of HRT, published in August, we were able to show that this effect is substantially greater for combined (oestrogen-progestagen) HRT than for oestrogen only HRT, and that the effects were similar for all specific types and doses of oestrogen and progestagen, for oral, transdermal and implanted HRT and for continuous and sequential patterns of use (Million Women Study Collaborators (2003) Lancet 362:419-427). Current users of oestrogen-progestagen HRT were at 2-fold increased risk of developing breast cancer and current users of oestrogen-only HRT were at 1.3-fold risk. The risk increased with increasing duration of use; 10 years’ use of oestrogen-progestagen HRT is estimated to result in 19 extra breast cancers per 1000 women aged 50-65, in addition to the 32 per 1000 expected in never users. This suggests that the use of HRT by women aged 50-64 in the UK over the past 10 years may have resulted in an extra 20,000 breast cancers. More information is needed on the effects of HRT on mortality from breast cancer and on the risk of other cancers, in particular endometrial cancer, but these results suggest that the benefits and risks of oestrogen-only versus oestrogen-progestagen HRT may need to be reassessed.
Future plans
Two new Million Women Study investigations are under way. Surgeon in training Dr. Toral Gathani has joined the Million Women Study to help assess patterns of treatment for breast cancer, and will use information on pathology to look at how HRT use may affect breast cancer of different types. The Million Women Study is also being extended to collect DNA samples from several thousand women, to allow us to consider genetic factors as well as environmental factors like HRT when looking at disease risk. Pilot studies for this Disease Susceptibility study will begin this year.
Million Women Study celebrates again!
The Million Women Study celebrated another milestone in May 2003: questionnaire scanning has been completed for all 1,384,461 million women recruited. We hope to have completed the collection of primary follow-up questionnaires for all the recruited women by March 2004.
Screening centres continue to provide information
Moya Simmonds, Elizabeth Hilton and Barbara Crossley are continuing to collect details of breast cancers diagnosed in Million Women Study participants. This information on pathology and clinical details will form a vital part of the next stage of Million Women Study analyses. The Million Women Study co-ordinating centre staff would like to thank staff at screening centres for their continuing support.
News from the Collaborators’ Meeting
The fifth annual Million Women Study Collaborators’ Meeting, was held at Lincoln’s Inn Fields on 16th June 2003. Recent findings were presented on breast cancer and cervix cancer from the Million Women Study, and on breast cancer in relation to alcohol and tobacco from the Collaborative Group on Hormonal Factors in Breast Cancer. We would like to thank Martin Vessey and Julietta Patnick for chairing the meeting.
