Community radiologists give widely different interpretations of the same mammogram, according to a study supported by the Agency for Healthcare Research and Quality (HS10591). In fact, younger, more recently trained radiologists had two to four times more false-positive readings (diagnosing possible cancer when there was none) than older radiologists. This finding from a real-world community setting bolsters similar evidence from earlier studies on radiologists' variability using test sets of mammograms.
In the current study, Joann G. Elmore, M.D., M.P.H., of the University of Washington School of Medicine, and her colleagues examined results from 24 community radiologists' interpretations of 8,734 screening mammograms from 2,169 women over an 8-½ year period. They found wide variation in how frequently different radiologists noted masses, calcifications, and other suspicious lesions. For instance, one radiologist did not observe any calcifications, while another radiologist noted calcifications in more than 20 percent of the films read.
The radiologists also varied widely in their diagnostic interpretations and recommendations for additional screens and biopsies. The rate of false-positive readings among the radiologists ranged from 2.6 percent to 15.9 percent. However, after adjustment for differences in patient, radiologist, and testing characteristics, the range of false-positive rates narrowed to 3.5 to 7.9 percent.
Women who were younger, were premenopausal, were using hormone replacement therapy at the time of the mammogram, had a family history of breast cancer, or had a previous biopsy were more likely to have a false-positive result. Also, more women who had mammograms in the 1990s were likely to have a false-positive result than women who had mammograms in the 1980s, perhaps due to the growing fear of malpractice litigation for delayed detection of breast cancer.
More details are in "Screening mammograms by community radiologists: Variability in false-positive rates," by Dr. Elmore, Diana L. Miglioretti, Ph.D., Lisa M. Reisch, Ph.D., and others, in the September 18, 2002 Journal of the National Cancer Institute 94(18), pp. 1373-1380.