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. 2003 Feb 10;88(3):362-5.
doi: 10.1038/sj.bjc.6600712.

Breast cancer incidence after the start of mammography screening in Denmark

A H Olsen  1 , A Jensen, S H Njor, E Villadsen, W Schwartz, I Vejborg, E Lynge
Affiliations

Breast cancer incidence after the start of mammography screening in Denmark

A H Olsen et al. Br J Cancer. .

Abstract

Mammography screening may lead to overdiagnosis of asymptomatic breast cancers, that would otherwise not have given rise to clinical symptoms. This aspect was studied in three regional screening programmes in Denmark, which started in Copenhagen municipality, Fyn county, and Frederiksberg municipality in 1991, 1993, and 1994, respectively. In these regions, we compared time trends in incidence of invasive breast cancer with the rest of Denmark. Since the number of clinical mammograms was relatively low, it was reasonable to assume that the breast cancer incidence outside the three screening regions represented the incidence of a population with low-intensity opportunistic screening. In Copenhagen and Fyn, a prevalence peak in incidence was seen during the first invitation round. During the subsequent invitation rounds, the incidence dropped to a level in line with the incidence expected without screening. The pattern was different in the small municipality of Frederiksberg, where the sensitivity was low during the first invitation round. Inclusion of screen-detected ductal carcinoma in situ cases did not change these results. The experiences from Copenhagen and Fyn show that organised mammography screening can operate without overdiagnosis of breast cancer.

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Figures

Figure 1
Figure 1
Number of mammography examinations in Denmark in women aged 50–69 during the years 1983–2000.
Figure 2
Figure 2
Cumulative risk (in per cent) of incident invasive breast cancer for women aged 50–69 in the three regions with organised mammography screening and in Denmark excluding the screening regions. The pattern in Frederiksberg probably reflects low sensitivity during the first invitation round.
See this image and copyright information in PMC

Comment in

  • Overdiagnosis of breast cancer in Denmark.
    Zahl PH. Zahl PH. Br J Cancer. 2004 Apr 19;90(8):1686; author reply 1687. doi: 10.1038/sj.bjc.6601738. Br J Cancer. 2004. PMID: 15083204 Free PMC article. No abstract available.

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