Questions About Cancer? 1-800-4-CANCER

Breast Cancer Screening (PDQ®)

Health Professional Version
Last Modified: 08/15/2014

Changes to This Summary (08/15/2014)

The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.


Added text to state that based on the 25-year follow-up from the Canadian National Breast Screening Study (CNBSS), a randomized controlled trial (RCT) of breast cancer screening, there is some uncertainty about the magnitude of benefit of mammography in the present day (cited Miller et al. as reference 3).

Added text to state that the best estimations of overdiagnosis come from either long-term follow-up of RCTs of screening or the calculation of excess incidence in large screening programs; although there are uncertainties with each approach, follow-up of the long-term CNBSS and well-conducted excess incidence studies in the United States and Scandinavia found that at least 20% of screen-detected breast cancers are overdiagnosed (cited Bleyer et al. as reference 7, Kalager et al. as reference 8, and Jørgensen et al. as reference 9).

Harms of Screening Mammography

Added text to state that Table 2 provides an overview of the estimated benefits and harms of screening mammography for 10,000 women who undergo annual screening mammography over a 10-year period (cited Pace et al. as reference 1).

Added Table 2, Estimated Benefits and Harms of Mammography Screening for 10,000 Women Who Undergo Annual Screening Mammography Over a 10-Year Period.

Added text to state that as shown in Table 2, the estimated number of women out of 10,000 who undergo annual screening mammography over a 10-year period with at least one false-positive result is 6,130 for women aged 40 to 50 years and 4,970 for women aged 60 years; the number of women with a false-positive resulting in a biopsy is estimated to range from 700 to 980, depending on age.

Added text to state that Table 2 shows the estimated number of women with breast cancers or ductal carcinoma in situ diagnosed during a 10-year period of screening 10,000 women that would never become clinically important; there was no overdiagnosis in the Health Insurance Plan study, which used old-technology mammography and clinical breast examination; overdiagnosis has become more prominent in the era of improved-technology mammography, but the benefits of newer-technology mammography over older-technology mammography have not been demonstrated.

This summary is written and maintained by the PDQ Screening and Prevention Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ NCI's Comprehensive Cancer Database pages.