"This finding suggests that many, if not most, of the presumptively abnormal mammographic interpretations in screening programs with high percentages of abnormal mammograms turn out to be false positives," say study leader Joann G. Elmore, M.D., of the Harborview Medical Center in Seattle, and her colleagues. False-positive mammograms can lead to unnecessary follow-up procedures (e.g., biopsies), higher medical costs, and anxiety for the patient.
Elmore and her colleagues analyzed data from 32 studies of community-based screening mammography programs to compare outcomes of mammographic readings between programs in North America and those in other countries. In each study, they looked at the percentage of mammograms considered abnormal, the percentage of women diagnosed with ductal carcinoma in situ (DCIS), and the percentage of women diagnosed with minimal disease.
The percentage of mammograms deemed abnormal by North American programs was 2 to 4 percentage points higher than it was in programs in other countries, even after adjusting for factors such as age of women screened and number of mammography readers for each examination (single vs. double). North American programs also reported a higher percentage of DCIS. However, a higher percentage of abnormal mammograms did not appear to be associated with a higher rate of breast cancers being diagnosed.
The authors stress caution in interpreting these findings. They explain that a number of factors may be contributing to the observed variation between North American programs and programs in other countries, including differences in the po
Contact: Linda Wang
Journal of the National Cancer Institute