As the prevalence of computer-assisted detection (CAD) use rises to nearly 80 percent of Medicare mammography exams, so do the associated costs, reaching nearly $300 million in Medicare costs for an eight year period between 2001 and 2009, according to a study published in the December issue of the JAMA Internal Medicine.

The CAD tool is used by radiologists to identify potentially malignant lesions, though research has suggested that false-positive rates rise with increased use of CAD in screening mammography and the detection of ductal carcinoma in situ (DCIS).

For this study, the researchers, including Joshua J. Fenton, MD, MPH, with the Department of Family and Community Medicine at the University of California, Davis, estimated the fraction of diagnostic tests, DCIS treatments and costs attributable to CAD dissemination in the Medicare population.

Using Medicare-linked data from 2001 to 2009, the researchers identified screening mammograms performed on female patients between the ages of 67 and 89 years old who were enrolled in Medicare. They classified mammograms by CAD use and computed the prevalence of annual CAD use. The team then estimated annual attributable fractions for diagnostic mammography, ultrasonography, biopsy and DCIS diagnoses.

The study showed the annual CAD prevalence among Medicare screening mammograms increased from 3.5 percent to 79.7 percent between 2001 and 2009. Additionally, by 2009, 18.2 percent of diagnostic mammograms, 5.3 percent of breast ultrasounds, 7.4 percent of breast biopsies and 11.9 percent of DCIS diagnoses were attributed to CAD.

“The long-term implications of increased DCIS detection in the Medicare population are uncertain,” the authors wrote. “On one hand, the intent of screening is to detect breast cancers earlier when treatments can be curative and less morbid. However, many DCIS lesions may be overdiagnosed, particularly in an older population.”

In the same time period (2001 to 2009), Medicare costs for CAD use totaled $278,564,950. Fenton and colleagues estimated that if CAD were used on all Medicare screening mammograms, the costs would exceed $67 million annually.

“Because of broad dissemination in the U.S., CAD likely accounts for a substantial fraction of diagnostic breast imaging, breast biopsies, and DCIS diagnoses among the Medicare population, with high resultant costs,” they concluded.