One Million Women Study
The One Million Women Study ( The Million Women Study ) is a British study on women's health. More than one million women between the ages of 50 and 64 took part in the study between 1996 and 2001, that is 53% of all women in this age group. The study is a joint project of the British organization Cancer Research UK and the national health system of Great Britain's National Health Service (NHS) and is additionally funded by the British Medical Research Council (UK) . The aim of the study is to answer open questions related to the factors that influence the health of women in this age group. The studies focus on the effects of hormone replacement therapy (HRT) during menopause on the health of women. The study confirmed the results of the US Women's Health Initiative ( Women's Health Initiative ; WHI) that women who take hormones to date, a higher risk of breast cancer than women who do not.
Study design
The One Million Women Study is a prospective, population-based cohort study in the UK. In the UK, all women between the ages of 50 and 64 who are registered with a general practitioner are regularly invited (every three years on average) for breast cancer screening at one of approximately 100 NHS screening centers. Between 1996 and 2001, all women invited for breast cancer screening at one of the 66 mammography screening centers cooperating with the study were invited to take part in the One Million Women Study. The women at these centers received a questionnaire together with the invitation to the breast cancer screening and were asked to fill it out and bring it to the screening appointment. Approximately 70% of the women participating in the screening submitted the completed questionnaire and were ready to take part in the study; that was more than 25% of British women over the age of 50. The One Million Women Study is the largest study of its kind in the world.
aims
The aim of the One Million Women Study is to conduct a cohort study of 1,000,000 British women to answer the following questions:
- How do hormone replacement therapies (HRT) with combination products made from estrogen and progestagen influence the risk of breast cancer?
- Does breast cancer screenings in women taking HRT supplements or oral contraceptives find breast cancer that is different in size and invasiveness from breast cancer in women who have never used these hormones?
- How does hormone replacement therapies affect breast cancer screening efficiency?
- How does hormone replacement therapy affect breast cancer mortality and mortality related to other diseases?
Results
HRT and breast cancer
The follow-up performed on more than 1 million women in the study confirmed the results of other recent studies that women who were taking HRT supplements at the time of the study were at an increased risk of breast cancer. Women who had taken HRT supplements in the past were not at an increased risk of breast cancer. The study was able to show that this effect is significantly greater when using combination preparations with estrogen and gestagen than when using monopreparations that only contain estrogen. The effects were similar for all specific types and dosages of estrags and progestogens and for the various forms of application (oral ingestion, transdermal patches or implants) and application schemes (continuous or sequential therapy). Women who used combination HRT preparations during the study were twice as likely to develop breast cancer, and women who used estrogen preparations were 1.3 times as likely to develop breast cancer. HRT use in women aged 50 to 64 years resulted in an estimated 20,000 additional breast cancers in the UK between 1993 and 2003.
HRT and cancer of the uterine lining
It is known that postmenopausal women who have not had a hysterectomy have an increased risk of endometrial cancer (cancer of the lining of the womb) when taking estrogen-only therapy. The follow-up carried out as part of the one million women study in more than 70,000 women confirmed this and shows that the risk of endometrial cancer is also increased in women who take tibolone . However, the risk is not increased in women taking HRT with a combination product. The change in uterine cancer risk also depends on the body mass index (BMI) of women; thinner women suffer more from the adverse effects of tibolone and estrogen-only supplements, while overweight women benefit more from the positive effects of combination products.
HRT and ovarian cancer
The results of the study show a small increase in ovarian cancer risk in women who use HRT supplements. Earlier studies had suggested such an increase, this has now been confirmed with the help of the large number of cases in the one million women study. The study evaluated the data from 948 576 postmenopausal women over a period of five years. Women who were taking HRT supplements at the time of the study were about 1.2 times more likely to develop and die from ovarian cancer than other women. For every 1,000 women using HRT supplements, there were 2.6 cases of ovarian cancer over five years, compared with 2.2 cases for all other women. The type of HRT (estrogen-only product, combination product with estrogen and progestagen or other HRT products including tribolone), the type of application (oral intake or transdermal patch) and the specific type of estrogen or progestogen did not affect the risk. The risk of ovarian cancer was not increased in women who had used HRT supplements in the past but no longer during the study. According to the results of the study, use of HRT supplements leads to an additional case of ovarian cancer per 2,500 women and an additional death from ovarian cancer per 3,300 women over a period of five years.
Summary
The editors of the study suggest that the results need to be viewed in the context of other risks and benefits of HRT. Breast cancer, uterine lining cancer and ovarian cancer together account for more than 40% of cancers in women in the UK. According to the results of the study, 19 out of 1,000 women between the ages of 50 and 69 who are not using HRT will develop one of these cancers over a five-year period. For every 1,000 women in this age group who use HRT supplements, an estimated 31 will become ill. The increase in risk is mainly due to an increase in breast cancers. Therefore, when using combination preparations with estrogen and gestagen, the risk increases more than when using estrogen-only preparations, because combination preparations increase the risk of breast cancer.
Impact of the study on public health
The results of the One Million Women Study and the WHI study had an impact on national health policies in the UK, e.g. B. through the recommendations of the Royal College of Obstetricians and Gynecologists and the Commission on Human Medicines on the prescription and use of hormone replacement therapy.
credentials
- ↑ Beral, V., Banks, E, Reeves, G .: Effects of estrogen-only treatment in postmenopausal women . In: JAMA . 292, No. 6, August 2004, p. 684; author reply pp. 685-686. doi : 10.1001 / jama.292.6.684-a . PMID 15304460 .
- ↑ Banks, E., Beral, V., Reeves, G .: Published results on breast cancer and hormone replacement therapy in the Million Women Study are correct . In: Climacteric . 7, No. 4, December 2004, pp. 415-416; author reply pp. 416-417. doi : 10.1080 / 13697130400014698 . PMID 15799614 .
- ↑ Gray, S .: Breast cancer and hormone-replacement therapy: the Million Women Study . In: Lancet . 362, No. 9392, October 2003, p. 1332; author reply p. 1332. doi : 10.1016 / S0140-6736 (03) 14598-9 . PMID 14575993 .
- ↑ Beral, V., Bull, D., Reeves, G .: Endometrial cancer and hormone-replacement therapy in the Million Women Study . In: Lancet . 365, No. 9470, 2005, pp. 1543-1551. doi : 10.1016 / S0140-6736 (05) 66455-0 . PMID 15866308 .
- ↑ Beral, V., Bull, D., Green, J., Reeves, G .: Ovarian cancer and hormone replacement therapy in the Million Women Study . In: Lancet . 369, No. 9574, May 2007, pp. 1703-1710. doi : 10.1016 / S0140-6736 (07) 60534-0 . PMID 17512855 .