Skip Navigation

This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow E-letters: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (10)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Duffy, S. W.
Right arrow Articles by Chen, H. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Duffy, S. W.
Right arrow Articles by Chen, H. H.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Annals of Oncology 14:1196-1198, 2003
© 2003 European Society for Medical Oncology

Original Paper

The Swedish Two-County Trial of mammographic screening: cluster randomisation and end point evaluation

S. W. Duffy1,+, L. Tabar2, B. Vitak3, M. F. Yen1, J. Warwick1, R. A. Smith4 and H. H. Chen5

1 Queen Mary University of London, London, UK; 2 Falun Central Hospital, Falun, Sweden; 3 University of Linköping, Linköping, Sweden; 4 American Cancer Society, Atlanta, GA, USA; 5 Institute of Preventive Medicine, National Taiwan University, Taipei, Taiwan

Received 19 July 2002; accepted 3 April 2003

Background:

The Swedish Two-County Trial has been criticised on the grounds of the cluster randomisation and alleged bias in classification of cause of death.

Patients and methods:

In the Two-County Trial, 77 080 women were randomised to regular invitation to screening (active study population, ASP) and 55 985 to no invitation (passive study population, PSP), in 45 geographical clusters. After ~7 years, the PSP was invited to screening and the trial closed. We analysed data using hierarchical statistical models to take account of cluster randomisation, and performed a conservative analysis assuming a systematic difference between ASP and PSP in baseline breast cancer mortality in one of the counties. We also analysed deaths from causes other than breast cancer and from all causes among breast cancer cases diagnosed in the ASP and PSP.

Results:

Taking account of the cluster randomisation there was a significant 30% reduction in breast cancer mortality in the ASP. Conservatively, assuming a systematic difference between ASP and PSP clusters in baseline breast cancer mortality, there was a significant 27% reduction in mortality in the ASP. Ignoring classification of cause of death, there was a significant 13% reduction in all-cause mortality in breast cancer cases in the ASP.

Conclusions:

Breast cancer mortality is a valid end point and mammographic screening does indeed reduce mortality from breast cancer. The criticisms of the Swedish Two-County Trial are unfounded.

Key words: breast screening, mammography, randomised trial


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Ann OncolHome page
P. Boyle
Global summit on mammographic screening
Ann. Onc., August 1, 2003; 14(8): 1159 - 1160.
[Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.