Overdiagnosis, Sojourn Time, and Sensitivity in the Copenhagen Mammography Screening Program

Authors

  • Anne Helene Olsen PhD,

    1. Cancer Research UK, Department of Epidemiology, Mathematics, and Statistics, Wolfson Institute of Preventive Medicine, Charterhouse Square, London, United Kingdom
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  • Olorunsola F. Agbaje PhD,

    1. Cancer Research UK, Department of Epidemiology, Mathematics, and Statistics, Wolfson Institute of Preventive Medicine, Charterhouse Square, London, United Kingdom
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  • Jonathan P. Myles PhD,

    1. Cancer Research UK, Department of Epidemiology, Mathematics, and Statistics, Wolfson Institute of Preventive Medicine, Charterhouse Square, London, United Kingdom
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  • Elsebeth Lynge,

    1. Institute of Public Health, University of Copenhagen, Copenhagen, Denmark
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  • Stephen W. Duffy MSc

    1. Cancer Research UK, Department of Epidemiology, Mathematics, and Statistics, Wolfson Institute of Preventive Medicine, Charterhouse Square, London, United Kingdom
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Address correspondence and reprint requests to: Anne Helene Olsen, PhD, Cancer Research UK, Department of Epidemiology, Mathematics and Statistics, Wolfson Institute of Preventive Medicine, Charterhouse Square, London, EC1M 6BQ, UK, or e-mail: stephen.duffy@cancer.org.uk.

Abstract

Abstract:  The goal of this research was to estimate the overdiagnosis at the first and second screens of the mammography screening program in Copenhagen, Denmark. This study involves a mammography service screening program in Copenhagen, Denmark, with 35,123 women screened at least once. We fit multistate models to the screening data, including preclinical incidence of progressive cancers and nonprogressive (i.e., overdiagnosed) cancers. We estimated mean sojourn time as 2.7 years (95% confidence interval [CI] 2.2–3.1) and screening test sensitivity as 100% (95% CI 99.8–100). Overdiagnosis was estimated to be 7.8% (95% CI 0.3–26.5) at the first screen and 0.5% (95% CI 0.02–2.1) at the second screen. This corresponds to 4.8% of all cancers diagnosed among participants during the first two invitation rounds and following intervals. A modest overdiagnosis was estimated for the Copenhagen screening program, deriving almost exclusively from the first screen. The CIs were very broad, however, and estimates from larger datasets are warranted. 

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