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Breast cancer mortality in Copenhagen after introduction of mammography screening: cohort study

BMJ 2005; 330 doi: (Published 27 January 2005) Cite this as: BMJ 2005;330:220
  1. Anne Helene Olsen, statistician (a.h.olsen{at},
  2. Sisse H Njor, statistician1,
  3. Ilse Vejborg, chief physician, Centre of Diagnostic Imaging2,
  4. Walter Schwartz, chief physician3,
  5. Peter Dalgaard, associated professor1,
  6. Maj-Britt Jensen, statistician, Danish Breast Cancer Cooperative Group2,
  7. Ulla Brix Tange, staff specialist, Department of Oncology2,
  8. Mogens Blichert-Toft, professor, Danish Breast Cancer Cooperative Group2,
  9. Fritz Rank, chief physician, Department of Pathology2,
  10. Henning Mouridsen, professor, Department of Oncology2,
  11. Elsebeth Lynge, professor1
  1. 1 Institute of Public Health, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
  2. 2 University Hospital Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen ⊘, Denmark
  3. 3 Mammography Screening Clinic, University Hospital Odense, Kl⊘vervænget 10, DK-5000 Odense, Denmark
  1. Correspondence to: A H Olsen
  • Accepted 15 November 2004


Objectives To evaluate the effect on breast cancer mortality during the first 10 years of the mammography service screening programme that was introduced in Copenhagen in 1991.

Design Cohort study.

Setting The mammography service screening programme in Copenhagen, Denmark.

Participants All women ever invited to mammography screening in the first 10 years of the programme. Historical, national, and historical national control groups were used.

Main outcome measures The main outcome measure was breast cancer mortality. We compared breast cancer mortality in the study group with rates in the control groups, adjusting for age, time period, and region.

Results Breast cancer mortality in the screening period was reduced by 25% (relative risk 0.75, 95% confidence interval 0.63 to 0.89) compared with what we would expect in the absence of screening. For women actually participating in screening, breast cancer mortality was reduced by 37%.

Conclusions In the Copenhagen programme, breast cancer mortality was reduced without severe negative side effects for the participants.


  • Contributors All the authors have contributed to the planning and reporting of the work described in the article. AHO is the guarantor.

  • Funding Danish Medical Research Council; Centre for Evaluation and Medical Technology Assessment in the Danish National Board of Health; the European Commission, Directorate-General SANCO, and Copenhagen Hospital Corporation.

  • Competing interest None declared.

  • Ethical approval Not required.

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