Ambiguous breast biopsies often “overinterpreted”

Pathologists’ tendency to overinterpret breast biopsies may be contributing to the problem of breast cancer overdiagnosis.

That’s according to a report this week in Annals of Internal Medicine with two OHSU co-authors, Heidi D. Nelson, M.D., M.P.H., and Patricia Carney, Ph.D. The researchers, including lead author Joann Elmore, M.D., M.P.H., at the University of Washington, compared the diagnostic findings of 115 practicing pathologists with the consensus findings of an expert panel of three pathologists.

The individual pathologists and the expert panel rendered a diagnosis based on a single pathology slide for each of 240 cases. Agreement with the consensus panel was above 97 percent when the diagnosis was benign and when it was invasive breast cancer. The less clear-cut cases posed more difficulty.

The study “further emphasizes the need to redefine ‘cancer’ and avoid using the term for lesions that are not destined to kill the patient.”

Nearly one in five women given a diagnosis of ductal carcinoma in situ, or DCIS, had a biopsy specimen interpreted as either benign or atypia by the consensus panel. (Atypia are benign lesions that contain breast cells multiplying into abnormal patterns and showing some of the early features of cancer).

“Our results suggest that overinterpretation of the pathologic findings may contribute to overdiagnosis and overtreatment of DCIS,” the authors concluded, noting that most women diagnosed with DCIS are offered lumpectomy and radiation therapy or total mastectomy, and they may also be offered adjuvant hormonal therapy for 5 to 10 years to reduce recurrence risk.

About half of breast biopsies with a diagnosis of atypia (53.6 percent) were interpreted as benign cases without atypia by the expert panel. Overdiagnosis of atypia may also lead to unnecessary interventions, the authors said. Patients diagnosed with atypia on a core biopsy are likely to have an excision biopsy and be considered for risk-reducing hormonal therapy.

The study “further emphasizes the need to redefine ‘cancer’ and avoid using the term for lesions that are not destined to kill the patient,” an accompanying editorial in the journal observed.

Variability in pathologists’ interpretations of individual breast biopsy slides: a population perspective by Joann G. Elmore, Heidi D. Nelson, Margaret S. Pepe, Gary M. Longton, Anna N.A. Tosteson, Berta Geller, Tracy Onega, Patricia A. Carney, Sara L. Jackson, Kimberly H. Allison, and Donald L. Weaver. Annals of Internal Medicine (2016)