Breast Density Exceeds Other Risk Factors for Breast Cancer

Women with high breast density have an increased risk of developing breast cancer, exceeding other known risk factors such as family history of the disease, personal history of benign lesions and later-in-life childbirth.

    Those are the findings of a new study conducted by researchers at the University of California, San Francisco (UCSF) and published in the journal JAMA Oncology.

    Researchers looked at risk factors in more than 200,000 women; of those women, 18,437 had varying stages of breast cancer and 184,309 did not have cancer. The women ranged in age from 40 to 74 and were enrolled in the Breast Cancer Surveillance Consortium, which is a national collaborative network of seven mammography registries.

    "We looked at all of the breast cancer cases in the Breast Cancer Surveillance Consortium, and basically found that the risk factor that explained the development of breast cancer, in the largest number of women, was high breast density," Karla Kerlikowske, M.D., researcher in the department of medicine and epidemiology and biostatistics at UCSF and senior author on the study, said in an interview with CURE. "Breast density is a common and strong risk factor, so it contributes a lot to the development of breast cancer." Overall, 4,747 (89.8 percent) premenopausal and 12,502 (95.1 percent) postmenopausal women with breast cancer had at least one breast cancer risk factor. However, breast density was the most prevalent risk factor for both premenopausal and postmenopausal women. Researchers noted that 39.3 percent of premenopausal and 26.2 percent of postmenopausal breast cancers could potentially be averted if all women with heterogeneously (more than half of the tissue in the breast is dense) or extremely (dense tissue is present in more than 75 percent of your breast) dense breasts shifted to scattered fibroglandular (which is mostly fat with a few dense areas) breast density.

    Additionally, the study reinforced the fact that obesity, too, can increase the odds of a woman developing breast cancer. Among postmenopausal women, 22.8 percent of breast cancers could potentially be averted if all overweight and obese women attained a body mass index of less than 25, noted the authors.

    "We can do something about obesity by choosing healthy foods and exercise," she said. "Breast density is also modifiable. Women who are very high-risk can take tamoxifen. Breast feeding is also thought to lower breast density, and the younger people are when they have their children and the more children they have also lowers breast density."

Source: QNA