Organized mammography screening does not result in overdiagnosis of cancer

(Breast Cancer-May 6, 2003)

"Mammography screening may lead to overdiagnosis of asymptomatic breast cancers, that would otherwise not have given rise to clinical symptoms," scientists in Denmark report.

"This aspect was studied in three regional screening programs in Denmark, which started in Copenhagen municipality, Fyn County, and Frederiksberg municipality in 1991, 1993, and 1994, respectively," wrote A.H. Olsen and colleagues, University of Copenhagen, Institute of Public Health.

"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," the researchers stated.

"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 researchers wrote.

"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 researchers added.

The researchers concluded: "The experiences from Copenhagen and Fyn show that organized mammography screening can operate without overdiagnosis of breast cancer."

Olsen and colleagues published their study in the British Journal of Cancer (Breast cancer incidence after the start of mammography screening in Denmark. Br J Cancer, 2003;88(3):362-365).

For more information, contact A.H. Olsen, University of Copenhagen, Institute of Public Health, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.

Publisher contact information for the British Journal of Cancer is: Nature Publishing Group, MacMillan Building, 4 Crinan St., London N1 9XW, UK.

The information in this article comes under the major subject areas of Oncology and Epidemiology. This article was prepared by Cancer Weekly editors from staff and other reports.

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