Norway study raises new U.S. mammogram overdiagnosis questions

An analysis showing significant mammogram overdiagnosis in Norway has raised new questions about mammograms in the U.S., where some say the overdiagnosis problem could be more rampant because of how early most women begin getting them.

MedPage Today: Breast Cancer Screening Under Fire Again 
A retrospective analysis in Norway found 6 to 10 cases of overdiagnosis for every 2,500 women invited to have mammographic screening, according to Mette Kalager, MD, of Harvard School of Public Health in Boston, and colleagues. In other words, the screening found a relatively large number of cancers that would not have become clinically significant during the woman's lifetime, Kalager and colleagues concluded in the April 3 issue of Annals of Internal Medicine (Smith, 4/2). 

Medscape: Mammography Screening Linked to Overdiagnosis of Cancer 
The investigators suggest that overdiagnosis not only poses a significant ethical dilemma but also burdens the patient and the health care system. ... Overdiagnosis is probably even more common in the United States than in Norway, because U.S. radiologists are more likely than European radiologists to report mammographic abnormalities, and because U.S. women often start annual mammography screening at 40 years of age, whereas Norwegian women start biennial screening at 50 years of age (Barclay, 4/2).