NEW YORK (Reuters Health) – Adding a clinical breast exam to mammography increases cancer detection rates and sensitivity – but it also increases rates of false positives and referrals for further testing, Canadian researchers report.

Using data from the Ontario Breast Screening Program, Dr. Anna M. Chiarelli, at the University of Toronto, and fellow researchers compared the results of breast cancer screening with and without clinical breast exams, which in all cases were done by specially trained nurses.

The study involved 232,515 women who were screened in 2002 or 2003 by both modalities, and 57,715 who had mammography alone in the same time period at centers that did not offer clinical breast exams. The women were between the ages of 50-69 years.

In the September 16 issue of the Journal of the National Cancer Institute, the researchers report that on initial screenings, sensitivity with the combination of techniques was 95%, versus 88.6% for mammography alone.

Cancer detection rates per 1000 women were roughly 7.5 with breast exam and mammography versus 5.4 without the breast exam.

However, the two techniques together also yielded a higher false positive rate compared to mammography alone: 12.5% versus 7.4%. They also resulted in more referrals for additional testing per 100 women: 13.1 versus 7.9.

Similar patterns were noted on subsequent screening, and these patterns persisted after adjustment for patient, provider, and facility characteristics.

“For each additional cancer detected by clinical breast exam per 10,000 women screened, there were an additional 55 false-positive screens,” Dr. Chiarelli’s team reports.

“Women should be informed of the risks and benefits of having a clinical breast examination in addition to mammography for breast screening,” the authors conclude.

In a related editorial, Dr. Mary B. Barton, at the Agency for Healthcare Research and Quality in Rockville, Maryland, and Dr. Joann G. Elmore of the University of Washington School of Medicine in Seattle, remark that more needs to be known about “the role of clinical breast examination in breast cancer screening before definitive recommendations for or against its use can be made.”

Drs. Barton and Elmore conclude, “The data presented by Chiarelli et al. suggest that clinical breast examination must be done well if it is to be done at all, with the acknowledgment that overall referrals and false-positive results will increase.”

Reference:
J Natl Cancer Inst 2009;101:1223-1225,1236-1243.