How Breast Density May Lead To Breast Cancer
Researchers from the Mayo clinic have discovered why breast density may increase a woman's risk of breast cancer, though they have known for some time that the risk exists. The scientists have discovered several possibilities about how breast tissue density may lead to breast cancer.
Studies presented at the Cancer Therapy & Research Center-American Association for Cancer Research (CTRC-AACR) San Antonio Breast Cancer Symposium shows that dense breast in women contain the types of cells that can more easily lead to breast cancer. Karthik Ghosh, M.D., a Mayo Clinic breast cancer researcher and physician who led one of two studies presented says, "We found a dramatic difference in tissue composition between dense and non-dense tissue in the breast."
In a second study, lead author Celine Vachon, Ph.D presented findings that the enzyme aromatase is more prevalent dense breast tissue. Aromatase may increase the risk of breast cancer by promoting estrogen, and important hormone long associated with breast cancer in women. Dr. Vachon says, "If aromatase is differentially expressed in dense and non-dense breast tissue, this could provide one mechanism by which density may increase breast cancer risk."
The study examined sixty women, age 40 to 85, none of whom had a history of breast cancer. The researchers obtained eight needle biopsies of the women's breasts, analyzing fat, milk glands, ductal cells, and connective breast tissue from the biopsies. Over half of tissue analyzed thus far showed that dense breast tissue contains much less fat that less dense breasts – 80% and 30% respectively. Dr. Ghosh suspects the increased connective tissue associated with breast density is the cause of increased cancer risk. Connective tissue contains more aromatase. According to Dr. Vachon, "If aromatase is differentially expressed in dense and non-dense breast tissue, this could provide one mechanism by which density may increase breast cancer risk." One more possible connection to breast cancer involved the number of milk ducts in breast tissue.
Decreased size and number of milk ducts has previously been associated with reduced risk of breast cancer. Dr. Vachon also found that women with dense breasts had larger milk ducts than those found in the biopsies of women with non-dense breast tissue.
The research is the first attempt by scientists to figure out why breast density increases cancer risk. "No one knows why density increases breast cancer risk, but we are attempting to connect the dots," Dr. Vachon says.
Further study results are pending. Not all of the women's breast tissue has been analyzed. The researchers plan to enroll more volunteers in hopes of discovering exactly why women with dense breasts are at increased risk of breast cancer.