Breast cancer a risk despite benign biopsy

Study finds many patients need to consider options


PHILADELPHIA - A breast biopsy that comes back benign is reassuring to most women, but about a third are at significantly higher risk of breast cancer and need to discuss their options, a new study concludes.

Those options include taking tamoxifen, undergoing genetic testing and supplementing regular mammography with breast MRIs.

"There are different categories of benign biopsies, and they convey different risks," said Mayo Clinic oncologist Lynn Hartmann, who led the study published in today's New England Journal of Medicine. "What we're trying to do is allay concern in women who really don't have an increased risk and solidify the extent of the increased risk in women who do."

Every year, about a million women who have suspicious lumps or mammograms undergo biopsies - tissue samples are removed for microscopic analysis - that are judged benign.

Doctors have long known that certain cell growth patterns are ominous, even though technically not malignant. However, there were questions about the degree of risk inherent in certain patterns and whether a family history of breast cancer intensified the risk.

The new study, the largest and most rigorous, identified more than 9,000 women who had benign biopsies at the Mayo Clinic from 1967 to 1991. The biopsy tissue was reanalyzed to classify it based on expert guidelines.

The women were followed for an average of 15 years, during which they developed 707 breast cancers. Their rates of cancer were compared with those from a state cancer registry.

About two-thirds of the women had benign growths made up of "nonproliferative" cells that were not rapidly dividing. These women had a tiny increase in risk, not enough to warrant extra measures to try to reduce it.

Thirty percent of the women had "proliferative" growths with rapidly multiplying cells and had an 88 percent greater chance of developing cancer.

The smallest subgroup - about 4 percent of the women - had the most worrisome growths, made up of abnormal-shaped, fast-dividing cells. They had a 324 percent greater risk of developing cancer.

Contrary to previous studies, a family history of cancer was not found to have a significant impact on risk.

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