“About 1.6 million breast biopsies are done every year in the U.S., yet in nearly half of the cases labeled atypia, our study indicates that there simply isn’t ‘concordance,’ meaning there is not agreement with a standard reference diagnosis,” explained Tosteson. In the study, a panel of three expert pathologists determined the reference diagnosis for each of 240 cases that included 23 cases of invasive breast cancer, 73 DCIS, 72 with atypical hyperplasia (atypia), and 72 benign cases without atypia.
The accuracy of breast biopsy diagnoses has not been well studied, but it is a critical element in treating women with breast disease appropriately. This work takes a new approach to informing what is known about the over- and under-interpretation for breast cancer and benign breast disease, and identifies the greatest clinical challenge for accurate interpretation. The study involved 115 participating pathologists from 8 states, providing a total of 6,900 breast pathology interpretations. The overall concordance rate was 75.3%, with a rate of 96% for biopsies with invasive carcinoma. The concordance rate for atypia was just 48%, and it was 84% for DCIS.
“Our findings show that, particularly for women with dense breasts, the lack of consensus in diagnoses of atypia or DCIS is considerable,” explained Onega. “The take-home message for women is that it’s not overly cautious to seek a second opinion with one of these diagnoses. In fact, it’s likely to be a good idea.”
The next steps for the Dartmouth investigators include assessing the various ways breast biopsies can be evaluated and their relative impact on patient management. Dartmouth’s Office of Cancer Comparative Effectiveness Research at Norris Cotton Cancer Center and the New Hampshire Mammography Network are actively supporting this ongoing research.