Originally published in Journal Watch General Medicine
by Allan S. Brett, MD
CBE was associated with 55 additional false-positives for each additional breast cancer detected.
Whether patients benefit when clinical breast examination (CBE) is added to screening mammography is unclear. Canadian researchers addressed this issue in an analysis of data from the Ontario Breast Screening Program, a network of screening centers. Two thirds of centers offer CBE (performed by specially trained nurses) plus mammography; one third offer mammography only.
Nearly 300,000 women (age range, 50–69) were screened during 2 years. Mammography plus CBE resulted in slightly higher rates of cancer detection, but also higher false-positive rates, than mammography alone. The authors calculate that, for every 10,000 screened women, 59 cancers were diagnosed with mammography alone, and 63 were diagnosed with CBE plus mammography. Thus, CBE detected 4 additional cancers per 10,000 women screened but also generated 219 additional false-positives (women referred for further evaluation who ultimately did not have cancer) per 10,000 screened women.
Comment: This study doesn’t carry the weight of a randomized trial, but its findings make intuitive sense and can be summarized as follows: For every 10,000 screened women, CBE (added to mammography) yielded 55 additional false-positives for every 1 additional case of breast cancer that was detected. Whether this trade-off is worthwhile depends on individual and societal values. One caveat: Because the nurses who performed these breast examinations took an average of 8 to 10 minutes per examination, the results might not reflect typical office practice.
Chiarelli AM et al. The contribution of clinical breast examination to the accuracy of breast screening. J Natl Cancer Inst 2009 Sep 16; 101:1236. (http://dx.doi.org/10.1093/jnci/djp241
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