Most Breast Lumps Do Not Mean Increase in Risk of Cancer, Study Finds
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Most women with breast lumps or other abnormalities that turn out to be noncancerous do not face a substantially greater risk of developing breast cancer later, especially if they have little family history of the disease, according to a new study.
However, certain “benign” growths are not so harmless and may be precursors to cancer, the study also found. Women with these may want to consider surgery or tamoxifen to lower their risk, doctors say.
The study was one of the largest to look at cancer risk according to the types of benign growths women had. It involved 9,087 women biopsied from 1967 to 1991 at the Mayo Clinic in Rochester, Minn. The findings were reported in last Thursday’s New England Journal of Medicine.
The information could be useful to a large number of women. In a decade of having mammograms, one out of five women will have a biopsy, and most biopsies will reveal benign growths, two specialists wrote in an accompanying editorial.
Overall, such women are 56% more likely to develop cancer during the next 15 years, the study found – the same conclusion previous ones reached. But the new work shows how much this risk varies – from very little to more than four times normal – depending on what the growths look like under the microscope.
“Many of these women are not at significantly increased risk for breast cancer, but it’s important that they know what their pathology showed” about the type of growth they had, said Dr. Lynn Hartmann, the Mayo doctor who led the work.
More than 1 million American women each year are diagnosed with benign breast conditions – suspicious clumps of cells, fluid-filled sacs called cysts, or solid masses called tumors.
In the Mayo study, 707 out of the 9,087 women with such conditions developed breast cancer, typically about a decade later.
The study did not settle one important question: whether benign lumps gradually turn into cancers or are just signs that the woman has a higher background risk and is therefore more likely to develop cancer in the rest of her breast tissue.
