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Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect

Emily Banks1*, Gillian Reeves2, Valerie Beral2, Diana Bull2, Barbara Crossley2, Moya Simmonds2, Elizabeth Hilton2, Stephen Bailey3, Nigel Barrett4, Peter Briers5, Ruth English6, Alan Jackson7, Elizabeth Kutt8, Janet Lavelle9, Linda Rockall10, Matthew G Wallis11, Mary Wilson12 and Julietta Patnick13

Author Affiliations

1 National Centre for Epidemiology and Population Health, Australian National University, ACT 0200, Australia

2 Cancer Research UK Epidemiology Unit, University of Oxford, Richard Doll Building, Roosevelt Drive, Oxford OX3 7LF, UK

3 Breast Screening Service, Princess of Wales Community Hospital, Stourbridge Road, Bromsgrove B61 0BB, UK

4 West of London Breast Screening Service, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK

5 Gloucestershire Breast Screening Service, Linton House, Thirlestaine Road, Cheltenham, Glos GL53 7AS, UK

6 The Breast Care Unit, Oxford Radcliffe Hospital NHS Trust, The Churchill Hospital, Old Road, Headington, Oxford OX3 7JH, UK

7 Patricia Massey Breast Screening Unit, Queen Alexandra Hospital, Cosham, Portsmouth, Hants PO6 3LY, UK

8 Avon Breast Screening, Central Health Clinic, Tower Hill, Bristol BS2 0JD, UK

9 North Lancashire Breast Screening Service, Royal Lancaster Infirmary, Ashton Court, Lancaster LA1 4GG, UK

10 The West Sussex Breast Screening Service, Worthing Hospital, Park Avenue, Worthing, West Sussex BN11 2DH, UK

11 Breast Screening Unit, Coventry and Warwick Hospital, Stoney Stanton Road, Coventry CV1 4FH, UK

12 Greater Manchester Breast Screening Service, The Nightingale Centre, Withington Hospital, Nell Lane, Manchester M20 0PT, UK

13 National Health Service Cancer Screening Programmes, Fulwood House, Old Fulwood Road, Sheffield S10 3TH, UK

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Breast Cancer Research 2006, 8:R8  doi:10.1186/bcr1364

Published: 23 December 2005



Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall.


A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome.


Overall, 399 (0.5%) participants were diagnosed with breast cancer and 2,629 (3.0%) had false positive recall. Compared to never users of HRT, the adjusted relative risk (95% CI) of false positive recall was: 1.62 (1.43–1.83), 1.80 (1.62–2.01) and 0.76 (0.52–1.10) in current users of oestrogen-only HRT, oestrogen-progestagen HRT and tibolone, respectively (p (heterogeneity) < 0.0001); 1.65 (1.43–1.91), 1.49 (1.22–1.81) and 2.11 (1.45–3.07) for current HRT used orally, transdermally or via an implant, respectively (p (heterogeneity) = 0.2); and 1.84 (1.67–2.04) and 1.75 (1.49–2.06) for sequential and continuous oestrogen-progestagen HRT, respectively (p (heterogeneity) = 0.6). The relative risk of false positive recall among current users appeared to increase with increasing time since menopause, but did not vary significantly according to any other factors examined, including duration of use, hormonal constituents, dose, whether single- or two-view screening was used, or the woman's personal characteristics.


Current use of oestrogen-only and oestrogen-progestagen HRT, but not tibolone, increases the risk of false positive recall at screening.