ArticlesBreast cancer and hormone-replacement therapy in the Million Women Study
Introduction
Results from randomised controlled trials and from observational studies show that current and recent use of hormone-replacement therapy (HRT) increases the risk of breast cancer.1, 2, 3, 4 However, the effect of HRT on mortality from breast cancer is unclear1, 2, 3, 4, 5 and use of HRT preparations containing oestrogen-progestagen combinations may be associated with a greater risk of breast cancer than preparations containing oestrogen alone.6, 7, 8, 9, 10 The Million Women Study, a cohort study of a quarter of British women aged 50–64 years, was set up chiefly to investigate the relation between various patterns of use of HRT and breast cancer incidence and mortality.11
Section snippets
Data collection and definitions
The National Health Service Breast Screening Programme (NHSBSP) invites all women in the UK aged 50–64 years for routine screening once every 3 years. From May, 1996, to March, 2001, the NHS breast-screening centres participating in the Million Women Study included the study questionnaire together with their letter of invitation for routine mammography.11 This letter is generally posted 2–6 weeks before the woman's screening appointment. The questionnaire is returned before women are screened
Results
These results are based on the follow-up of 1084110 women recruited between 1996 and 2001, who were flagged on the NHS Central Registers and who had not been registered as having had cancer before they joined the Million Women Study. The average age of the women at recruitment was 55·9 years, and the average period of follow-up was 2·6 years for analyses of the cancer incidence and 4·1 years for analyses of mortality. During the follow-up period, 9364 incident invasive breast cancers and 637
Discussion
The results of this study confirm previous findings that current and recent use of HRT increases the risk of breast cancer,1, 2, 3, 4, 5, 6, 7, 8, 9, 10 but also provides new and reliable information about the effects of various patterns of use. The Million Women Study was set up to examine the effect of HRT on breast cancer incidence and mortality. Study participants were recruited at the time of their triennial invitation for routine mammography by the NHSBSP. The programme provides a routine
References (24)
- et al.
Evidence from randomised trials on the long-term effects of hormone replacement therapy
Lancet
(2002) Breast cancer and hormone replacement therapy: collaborative reanalysis of data from 51 epidemiological studies of 52 705 women with breast cancer and 108411 women without breast cancer
Lancet
(1997)Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial
JAMA
(2002)- et al.
Influence of estrogen plus progestin on breast cancer and mammography in healthy postmenopausal women: the Women's Health Initiative randomised trial
JAMA
(2003) - et al.
Use of HRT and the subsequent risk of cancer
J Epidemiol Biostat
(1999) - et al.
The risk of breast cancer after estrogen and estrogen-progestin replacement
N Engl J Med
(1989) - et al.
Breast cancer risk following long-term oestrogen and oestrogen-progestin-replacement therapy
Int J Cancer
(1999) - et al.
Menopausal estrogen and estrogen-progestin replacement therapy and breast cancer risk
JAMA
(2000) - et al.
Effect of Hormone replacement therapy on breast cancer risk: estrogen versus estrogen plus progestin
J Natl Cancer Inst
(2000) - et al.
Relationship between long durations and different regimens of hormone therapy and risk of breast cancer
JAMA
(2003)
The Million Women Study: design and characteristics of the study population
Breast Cancer Res
Comparison of various characteristics of women who do and do not attend for breast cancer screening
Breast Cancer Res
Cited by (2950)
Progestins and breast cancer hallmarks: The role of the ERK1/2 and JNK pathways in estrogen receptor positive breast cancer cells
2024, Journal of Steroid Biochemistry and Molecular BiologyNew advances in menopause symptom management
2024, Best Practice and Research: Clinical Endocrinology and MetabolismEffects of Artemisia annua L. on postmenopausal syndrome in ovariectomized mice
2023, Journal of EthnopharmacologyEstrogen receptor β exerts neuroprotective effects by fine-tuning mitochondrial homeostasis through NRF1/PGC-1α
2023, Neurochemistry InternationalTargeting breast cancer using phytoconstituents: Nanomedicine-based drug delivery
2023, European Journal of Medicinal Chemistry Reports