Intended for healthcare professionals


Too much mammography

BMJ 2014; 348 doi: (Published 11 February 2014) Cite this as: BMJ 2014;348:g1403
  1. Mette Kalager, medical doctor and researcher123,
  2. Hans-Olov Adami, professor124,
  3. Michael Bretthauer, professor1256
  1. 1Department of Health Management and Health Economics, University of Oslo, Oslo, Norway
  2. 2Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
  3. 3Department of Research and Development, Telemark Hospital, Skien, Norway
  4. 4Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  5. 5Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway
  6. 6Department of Medicine, Sørlandet Hospital Kristiansand, Kristiansand, Norway
  1. Correspondence to: M Kalager mette.kalager{at}

Long term follow-up does not support screening women under 60

Before being widely implemented, mammography screening was tested in randomised controlled trials in the 1960s to 80s. Meta-analyses of these trials showed a relative reduction in deaths from breast cancer of between 15% and 25% among women aged 50 to 69.1 2 3 Only the Canadian National Breast Screening Study showed no reduction in breast cancer mortality.1 2 3 This large randomised controlled trial compared physical breast examination with combined physical breast examination and annual mammography in women aged 40 to 59.1 2 3

In a linked paper (doi:10.1136/bmj.g366), Miller and colleagues present the results for up to 25 years of follow-up in the Canadian study.4 No difference in breast cancer mortality was observed between the mammography and control arms, whereas a significant excess incidence of invasive breast cancer was observed in the mammography arm, resulting in 22% overdiagnosis. This means that 22% of screen detected invasive cancers would not have reduced a woman’s life expectancy if left undetected.

The major strengths of this study include its randomised design, intense intervention with …

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