Breast biopsies are good at telling the difference between healthy tissue and cancer, but less reliable for identifying more subtle abnormalities, a new study finds.
Because of the uncertainty, women whose results fall into the gray zone between normal and malignant — with diagnoses like “atypia” or “ductal carcinoma in situ” — should seek second opinions on their biopsies, researchers say. Misinterpretation can lead women to have surgery and other treatments they do not need or to miss out on treatments they do need.
The new findings, reported Tuesday in JAMA, challenge the common belief that a biopsy is the gold standard and will resolve any questions that might arise from an unclear mammogram or ultrasound.
In the United States, about 1.6 million women a year have breast biopsies; only about 20 percent of the tests find cancer. Ten percent identify atypia, a finding that cells inside breast ducts are abnormal, but not cancerous. About 60,000 women each year are found to have ductal carcinoma in situ, or D.C.I.S., which also refers to abnormal cells that are confined inside the milk ducts and so are not considered invasive; experts disagree about whether D.C.I.S. is cancer.
“It is often thought that getting the biopsy will give definitive answers, but our study says maybe it won’t,” said Dr. Joann G. Elmore, a professor at the University of Washington School of Medicine in Seattle and the first author of the new study on the accuracy of breast biopsies.
Her team asked pathologists to examine biopsy slides, then compared their diagnoses with those given by a panel of leading experts who had seen the same slides. There were some important differences, especially in the gray zone.
An editorial in JAMA said the findings were “disconcerting” and that the study should be a “call to action” for pathologists and breast cancer scientists to improve the accuracy of biopsy readings, by consulting with one another more often on challenging cases and by creating clearer definitions for various abnormalities so that diagnoses will be more consistent and precise. The editorial also recommended second opinions in ambiguous cases.
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