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Br J Cancer. 2016 May 24;114(11):1269-76. doi: 10.1038/bjc.2016.90. Epub 2016 Apr 28.

Meta-analysis of breast cancer mortality benefit and overdiagnosis adjusted for adherence: improving information on the effects of attending screening mammography.

Author information

1
Sydney School of Public Health, The University of Sydney, Edward Ford Building (A27), Sydney, NSW 2006, Australia.
2
Centre for Research in Evidence Based Practice, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4229, Australia.
3
Screening & Test Evaluation Program (STEP), Sydney School of Public Health, The University of Sydney, Edward Ford Building (A27), Sydney, NSW 2006, Australia.
4
Centre for Medical Psychology & Evidence-based Decision-making (CeMPED), Sydney School of Public Health, The University of Sydney, Edward Ford Building (A27), Sydney, NSW 2006, Australia.

Abstract

BACKGROUND:

Women require information about the impact of regularly attending screening mammography on breast cancer mortality and overdiagnosis to make informed decisions. To provide this information we aimed to meta-analyse randomised controlled trials adjusted for adherence to the trial protocol.

METHODS:

Nine screening mammography trials used in the Independent UK Breast Screening Report were selected. Extending an existing approach to adjust intention-to-treat (ITT) estimates for less than 100% adherence rates, we conducted a random-effects meta-analysis. This produced a combined deattenuated prevented fraction and a combined deattenuated percentage risk of overdiagnosis.

RESULTS:

In women aged 39-75 years invited to screen, the prevented fraction of breast cancer mortality at 13-year follow-up was 0.22 (95% CI 0.15-0.28) and it increased to 0.30 (95% CI 0.18-0.42) with deattenuation. In women aged 40-69 years invited to screen, the ITT percentage risk of overdiagnosis during the screening period was 19.0% (95% CI 15.2-22.7%), deattenuation increased this to 29.7% (95% CI 17.8-41.5%).

CONCLUSIONS:

Adjustment for nonadherence increased the size of the mortality benefit and risk of overdiagnosis by up to 50%. These estimates are more appropriate when developing quantitative information to support individual decisions about attending screening mammography.

PMID:
27124337
PMCID:
PMC4891513
DOI:
10.1038/bjc.2016.90
[Indexed for MEDLINE]
Free PMC Article

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