SEATTLE—Double reading mammograms increases breast cancer detection rates but not without substantial costs, according to a study done at Fletcher Allen Health Care, Burlington, Vermont, and presented at the 101st Annual Meeting of the American Roentgen Ray Society.
"When we set out to do double reading, our goal was to detect more breast cancers," said Susan Harvey, MD, assistant professor of radiology, University of Vermont College of Medicine. "We also wanted to attempt to maintain tolerable recall rates and to have some attempt at cost-effectiveness." Costs are a concern because double reading is not a billable service for most radiologists, she explained.
The second read at Fletcher Allen Health Care is designed to be a rapid read, Dr. Harvey said. "It takes between 30 seconds and a minute per case, depending on the radiologist and the case," she said. The second reader in this method can add but not delete recalls, she noted.
A total of 25,368 screening mammograms were double read. The double reading required an extra 1.5 hours per day or 375 hours per year, for a 0.18 full-time equivalent. "You could do the math in your practice and have some sense of what that time would cost you," Dr. Harvey commented.
The total recall rate was about 14%; the first reader’s interpretation was responsible for 12.6% of these recalls, and the second reader’s interpretation was responsible for 1.5% of these recalls.
The total biopsy rate for the screening population was 2.66%; the first reader’s interpretation initiated 2.5% of these biopsies, and the second reader’s interpretation initiated 0.2%, Dr. Harvey said. Overall, 20.6% of biopsies led to the diagnosis of malignancy; the malignant biopsy rate was 20.2% for the first reader and 26.2% for the second reader.
Of the 139 total malignancies detected, 11 were detected by the second reader for an increase of 7.9% in the cancer detection rate, Dr. Harvey said. Among these 11 cancers, 4 were classified as ductal carcinoma in situ, and 7 as invasive ductal cancers. All but one of the invasive ductal cancers were stage I.
The total cost of the mammography, ultrasound, biopsies, and pathology services generated by the second read was $111,100, Dr. Harvey said. This amounted to $10,100 per cancer for the 11 additional cancers detected. "If you divide that over all of the women screened in this period, our additional charges added up to $4.38 per screening mammogram," she noted.
Based on these findings, the center has modified its second-read procedure, she said, in an effort to decrease recall rates and costs. Now, if the second reader interprets the mammogram differently than the first reader, a third radiologist is brought in to discuss the case, and a consensus decision is made.
Dr. Harvey pointed out that the study may have underestimated the benefits of the second read. "We did not include the savings due to diagnosis of earlier-stage cancers. We know that earlier-stage cancers cost less to treat, use less resources, and have better survival," she said. "There is also the potential for less litigation exposure with double reading."
