Breast Density Linked To Increased Risk Of Breast Cancer, Study Says

Women with dense breasts are about three times more likely to develop breast cancer, compared with women with less dense breasts, according to a study published in the Jan. 18 issue of the New England Journal of Medicine, the Wall Street Journal reports (Winstein, Wall Street Journal, 1/18). The density of a breast is defined as the percentage of breast tissue that is not clearly visible on a mammogram, according to Toronto's Globe and Mail. For the study, Norman Boyd, an investigator at the Campbell Family Institute for Breast Cancer Research at Princess Margaret Hospital in Toronto, and colleagues compared the records of 1,112 women who were diagnosed with breast cancer between 1981 and 2006 with an equal number of women who did not develop breast cancer. The study found that women whose breast density was 75% or more were 4.7 times more likely to develop breast cancer compared with those whose density was under 10%. Women with dense breasts also were 18 times more likely with find cancerous tumors within one year of a negative mammogram, according to the study (Picard, Globe and Mail, 1/18). About 16% of all breast cancer cases and 25% of cases in women younger than age 56 in the study were among women who had a breast density of more than 50% (Donn, AP/Spokane Spokesman-Review, 1/17). According to the Journal, after results are published from another study funded by the National Cancer Institute and Avon Products, the American Cancer Society will consider whether to recommend that women with dense breasts receive additional screening with an ultrasound. Wendi Berg, a physician leading the Avon study, said women with dense breasts should consider having a digital mammogram conducted by a breast specialist, as opposed to a film-based mammogram. In an accompanying NEJM editorial, physician Karla Kerlikowske writes that physicians should discuss the breast density issue with patients (Wall Street Journal, 1/18).

The study is available online.

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