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Meta-Analysis
. 2009 Jul 9:339:b2587.
doi: 10.1136/bmj.b2587.

Overdiagnosis in publicly organised mammography screening programmes: systematic review of incidence trends

Karsten Juhl Jørgensen  1 , Peter C Gøtzsche
Affiliations
Meta-Analysis

Overdiagnosis in publicly organised mammography screening programmes: systematic review of incidence trends

Karsten Juhl Jørgensen et al. BMJ. .

Abstract

Objective: To estimate the extent of overdiagnosis (the detection of cancers that will not cause death or symptoms) in publicly organised screening programmes.

Design: Systematic review of published trends in incidence of breast cancer before and after the introduction of mammography screening.

Data sources: PubMed (April 2007), reference lists, and authors. Review methods One author extracted data on incidence of breast cancer (including carcinoma in situ), population size, screening uptake, time periods, and age groups, which were checked independently by the other author. Linear regression was used to estimate trends in incidence before and after the introduction of screening and in older, previously screened women. Meta-analysis was used to estimate the extent of overdiagnosis.

Results: Incidence data covering at least seven years before screening and seven years after screening had been fully implemented, and including both screened and non-screened age groups, were available from the United Kingdom; Manitoba, Canada; New South Wales, Australia; Sweden; and parts of Norway. The implementation phase with its prevalence peak was excluded and adjustment made for changing background incidence and compensatory drops in incidence among older, previously screened women. Overdiagnosis was estimated at 52% (95% confidence interval 46% to 58%). Data from three countries showed a drop in incidence as the women exceeded the age limit for screening, but the reduction was small and the estimate of overdiagnosis was compensated for in this review.

Conclusions: The increase in incidence of breast cancer was closely related to the introduction of screening and little of this increase was compensated for by a drop in incidence of breast cancer in previously screened women. One in three breast cancers detected in a population offered organised screening is overdiagnosed.

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Conflict of interest statement

Competing interests: None declared.

Figures

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Fig 1 Selection of core articles
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Fig 2 Incidence of invasive breast cancer per 100 000 women in UK
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Fig 3 Incidence of invasive breast cancer and carcinoma in situ per 100 000 women in Manitoba, Canada
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Fig 4 Incidence of invasive breast cancer per 100 000 women in New South Wales, Australia
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Fig 5 Incidence of invasive breast cancer per 100 000 women in Sweden
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Fig 6 Incidence of invasive breast cancer per 100 000 women in Akershus, Oslo, Rogaland, and Hordaland counties in Norway
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Fig 7 Incidence of invasive breast cancer per 100 000 women in counties other than Akershus, Oslo, Rogaland, and Hordaland in Norway
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Fig 8 Meta-analysis of overdiagnosis of breast cancer (including carcinoma in situ) in publicly available mammography screening programmes
See this image and copyright information in PMC

Comment in

References

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