How important is breast density—the amount of non-fatty tissue in the breast—in determining a woman’s risk of cancer? Judging from the alarm bells set off by everyone from women’s health advocates to the governor of New York, you’d think the answer is very.
Four states—New York, Connecticut, Virginia and Texas—require that women be informed if their mammograms show they have dense breasts, with Connecticut mandating insurance coverage for follow-up ultrasounds. An advocacy group, Are You Dense, Inc. (Areyoudense.org), is also raising awareness about the issue.
But how strong is the density/cancer connection? “As the concept of breast density has advanced, women think they have a very serious problem when they may not,” says Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society (ACS).
Reproductive-age women typically have more glandular, ductal and fibrous connective tissue than fatty breast tissue, but that tends to change with age. The American College of Radiology (ACR) estimates that 10 percent of women have breasts that are nearly all fat; 10 percent have extremely dense breasts; the rest fall somewhere in between.
Both connective tissue and tumors appear white on mammograms, making it difficult to spot cancers, says Dr. Daniel B. Kopans, a member of the ACR Breast Imaging Communications Committee. But that’s not all: Something may be going on in dense breast tissue that raises risk. A 2011 study reported that women with the most density had over three times the risk of breast cancer compared with women with lower density.
Researchers are continuing to look into the issue. For now, “knowing a woman has dense breasts can alert her physician to the fact that he should be more careful with the clinical breast exam,” says Kopans. The good news: A recent study found that breast density doesn’t raise the risk of dying from breast cancer.
If you’re concerned, ask your doctor about your breast density. While ultrasound and MRIs can find tumors that aren’t visible on mammograms, routine screening with these tests is not currently recommended for women with dense breasts.
Until more research is completed, breast density should be viewed as simply another piece of the puzzle in understanding the disease that will strike more than 226,000 women this year. “It is one part of a very large picture of health,” Lichtenfeld says.