Comments and Response on the USPSTF Recommendation on Screening for Breast Cancer FREE

TO THE EDITOR:

The data search for published evidence from the randomized, controlled trials (RCTs) used by the U.S. Preventive Services Task Force (USPSTF) in its breast cancer screening recommendation (1) ended in December 2008. In June 2009, Holmberg and colleagues (2) presented a review of the data from the Swedish Two-County Trial, which showed that the methods used in the previous overview of the 2 Swedish trials (3) “resulted in a reduction of the estimate of the effect of screening.” Unfortunately, these erroneous data from the early overview (3) were used for both the 2002 and 2009 USPSTF evaluations.

The USPSTF evaluation (1) and supporting articles are plagued with ambiguity over the terms “screen” and “screening” when used alone and in conjunction with the term “mammography.” Whereas the evidence of benefit has been drawn exclusively from intention-to-treat publications, the numerical conclusions have been directly applied by the USPSTF to the individual woman seeking advice from her physician. If the USPSTF evaluation is taken at face value, women will be told the estimated benefit of receiving an invitation to participate in a mammography screening program. This estimated benefit is considerably lower, by a factor of approximately 1.4, than the actual benefit of mammography (4). On the contrary, the harms estimated by the USPSTF are not calculated on an intention-to-treat basis, which introduced bias into the risk–benefit calculations.

The benefits of regular mammography were measured in Sweden by using the ongoing service screening programs (5), and results for women aged 40 to 49 years have been submitted for publication. These comprehensive service screening data more closely answer the question posed by the USPSTF concerning the benefits resulting from regular mammography versus no mammography than do the historical RCT data, which were designed to answer a different question.

Peter B. Dean, MD

University of Turku Faculty of Medicine and Turku University Hospital

20520 Turku, Finland