Medical Examination centers that offered clinical breast examination in addition to mammography were more likely to detect breast cancer than centers offering mammography alone, but also far more likely to produce false positives, a Canadian study found.

The study is published in the August 31, 2009 in the Journal of the National Cancer Institute.

To resolve the controversy over whether adding clinical breast examination to mammography improves the accuracy of breast screening, Anna Chiarelli of Cancer Care Ontario and her colleagues compared the results of 290,000 women aged 50 and 69 tested between January 2002 and December 2003.

The Canadian researchers found that the sensitivity of referrals was higher for women who were screened at centers that offered clinical breast examination and mammography than for women who were screened at centers that did not offer clinical breast examination. But, women without cancer who were screened at centers that offered clinical breast examination had a higher false-positive rate than women screened at centers that offered only mammography.

Overall, we found higher breast cancer detection rates and sensitivities for [clinical breast examination] referral than those previously found in other community-based studies, which suggests that the accuracy of [clinical breast examination] can be improved in screening programs that offer high-quality [clinical breast examinations] by specially trained nurses, the authors write. However, they note, the benefits of adding clinical breast examination must be weighed against potential risks and costs due to false-positive results and the anxiety associated with additional evaluations.

Their research was supported by a grant from the Canadian Breast Cancer Foundation–Ontario Region.