Pathologists often disagree on breast biopsy results when diagnosing DCIS

A study applying B-Path (Breast Pathology) Study results to patient populations found that pathologists disagree with one another about 8 percent of the time when diagnosing a single breast biopsy slide. Discordance was more likely in cases of DCIS or atypia, with a tendency toward overdiagnosing disease. The findings are published in Annals of Internal Medicine.

Results of the B-Path Study, an evaluation of diagnostic agreement among pathologists interpreting breast biopsy specimens, raised concerns about the accuracy of breast cancer diagnoses in general clinical practice. However, the study was not intended to reflect population impact. To provide a more clinically relevant assessment of accuracy than previously reported, researchers analyzed the B-Path Study data using U.S. population-adjusted estimates. The researchers estimated the probability that a pathologist's interpretation of a single breast biopsy slide would be confirmed by a consensus-based reference standard derived from three expert breast pathologists interpreting the same slide. For example, if a single slide from a woman's biopsy was interpreted as DCIS, how likely is it that her slide would get the same diagnosis from a panel of three expert pathologists?

The researchers found that pathologists were likely to agree on invasive breast cancer diagnoses, but agreement was substantially lower for interpretations of DCIS and atypia. For example, 1 in 5 women with an initial diagnosis of DCIS would have her biopsy specimen interpreted as atypia or benign by the reference consensus panel and half of the women with atypia would have their diagnosis downgraded to benign without atypia.

According to the authors, noninvasive but potentially high-risk breast lesions represent a gray area in medicine; there is not always a "right" or "wrong" diagnosis. They suggest that women with borderline findings may benefit from revised guidelines for clinical treatment and management.