18 Mar Pathologists Don’t Always Agree On Breast Biopsy Atypia or DCIS
MedicalResearch.com Interview with:
Joann G. Elmore M.D., M.P.H.
Professor of Medicine,
Adjunct Professor of Epidemiology,
University of Washington School of Medicine
Harborview Medical Center
Seattle, WA 98104-2499
MedicalResearch: What is the background for this study? What are the main findings?
Dr. Elmore: It is estimated that 1.6 million women in the United States each year undergo a breast biopsy. By interpreting these biopsies under the microscope, pathologists provide diagnoses on a spectrum from benign, to atypia, to ductal carcinoma in situ (DCIS), to invasive cancer. Using these diagnostic classifications, clinical doctors work with their patients to decide if they are at increased risk of developing breast cancer in the future, which can lead to additional surveillance, or how to treat them when the diagnosis is invasive breast cancer. As misclassification of breast lesions by pathologists may contribute to overtreatment and undertreatment of breast disease, we decided to study the accuracy of breast pathology diagnoses in the U.S.
In the Breast Pathology (B-Path) Study, we used a set of 240 breast biopsy cases to evaluate the interpretive accuracy of 115 U.S. pathologists who were actively interpreting breast biopsies in their clinical practices. Their diagnoses were compared with reference diagnoses established by a consensus panel of experienced breast pathologists. When the panel members each independently diagnosed the slides pre-consensus, they agreed unanimously on 75 percent of their diagnoses; ninety percent of the panel members’ initial independent diagnoses agreed with the final consensus-derived reference diagnoses.
When comparing participating pathologists’ diagnoses to the reference diagnoses, we found overall agreement for 75 percent of interpretations. The concordance rate for invasive breast cancer was reassuringly high at 96 percent, and fairly high for benign findings without atypia at 87 percent. However, concordance was lower for atypia at 48 percent and for DCIS at 84 percent. This means that nearly one out of five pathologists disagreed on the diagnosis of DCIS. We found disagreement with the reference diagnosis to be statistically more frequent when pathologists had lower weekly case volumes or worked in smaller labs. Disagreement was also statistically significantly more likely when the patient had dense breast tissue on mammogram; however, the absolute difference was small. Our accuracy findings were not altered when we used different methods of defining the reference diagnosis.
MedicalResearch: What should clinicians and patients take away from your report?
Dr. Elmore: First, patients should be reassured that pathologists have high accuracy diagnosing invasive breast cancer.
Second, there may be some cases that defy pathologists’ ability to give a diagnosis that clearly reflects the biology of the lesion. Even experienced pathologists specializing in breast pathology had variability in diagnosing atypia and DCIS.
Finally, a wait-and-see approach or obtaining a second opinion may be preferable to immediate action for abnormalities noted on screening mammography and for diagnoses of atypia and DCIS, given this diagnostic variation and biologic uncertainty.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. Elmore: Future research is needed to evaluate approaches to improving diagnostic accuracy, such as through obtaining second opinions on biopsies or using molecular markers to help define the underlying biology of the diagnoses.
MedicalResearch.com Interview with: Joann G. Elmore M.D., M.P.H. (2015). Pathologists Don’t Always Agree On Breast Biopsy Atypia or DCIS