Researchers, over the last few years, have been studying the relationship of cancer and the composition of breast tissue. Breast tissue consists mainly of ductal (milk glands), fat, and connective tissue. Because fat cells cannot become cancerous, the research theory was that if a breast had a higher volume of connective and ductal tissue rather than fatty tissue, then the greater the risk of developing breast cancer. A recent study is attempting to conclude what physicians have suspected, breast density increases a woman’s risk of breast cancer. Now armed with this new research data, the questions begin. What do physicians do with this information? How do physicians apply this knowledge when caring for patients? Should women be told density status?

Breast Tissue

Every woman’s breasts are made up of differing amounts of tissue types. In order to study breast density, researchers studied identical and fraternal female twins and determined that genetics accounted for approximately 60% of breast density variation. Age was also a major factor affecting breast density. Post-menopausal women have breasts that are primarily made up of fatty tissue, while 75 – 80% of pre-menopausal women have denser breast tissue. Only on mammogram can the density of a breast be measured. And just because a breast is dense does not mean cancer will develop, only that the risks are higher.

"Science" Research Article

An article was recently published in the September 9, 2005 issues of Science titled "Dissecting a Hidden Breast Cancer Risk" discussing the relationship of the risk between breast density and breast cancer. According to Steve Cummings, M.D., FACP an internationally recognized expert on epidemiology, "Only two other factors are known to increase a woman’s risk for developing breast cancer, age and breast cancer genes BRCA1 or BRCA2." And despite the connection between breast cancer and breast density it is not entirely clear as to why or how it increased the likelihood of breast cancer development. With support of the Daniel and Phyllis Da Costa Fund, Dr. Cummings is collaborating with researchers at the Royal Marsden Hospital in London, whose mission is to find ways to identify women at high risk for breast cancer. Together, they plan to develop new methods that can predict a woman’s chance of developing the disease, as well as learn about potential means for prevention.

What Women Can Do

What can women with dense breasts do? Extra mammogram screening–except mammography does not always catch tumors in dense breasts; alter breast tissue through changing to a low-fat diet–this has not been proven; preemptive drug therapy with tamoxifen, raloxifene, or lasofoxifene–these are currently being tested in large clinical trials. Women can participate in a clinical trial at California Pacific Medical Center. We invite you to join us in advancing the investigation of this important research question. We need women volunteers who are undergoing mammography to donate a small amount of blood (3 teaspoons) for this unique breast cancer study. For information on how to participate call us at 415-600-2780.