Before defining dense breast tissue, it’s important to understand the structures of the breast. The main function of breasts is to make milk for breastfeeding a baby. The raised area on the outside is the nipple. Surrounding the nipple is darker colored skin called the areola.
The inside is made up of glandular, fat (adipose), and supportive tissue. A system of lymph nodes, called the internal mammary chain, runs through the center of the chest.
Glandular tissue consists of a complex network designed to carry milk to the nipple. This glandular part of the breast is divided into sections called lobes. Within each lobe are smaller bulbs, called lobules, which produce milk. Milk travels through small ducts, which come together and connect into larger ducts designed to hold the milk. The ducts end at the nipple.
The rest of the breast consists of fatty tissue and connective tissue that provide shape and support. There are nerves, blood vessels, and lymphatic vessels. Breast tissue extends from the breastbone near the middle of the chest all the way to the armpit area.
The lymph vessels of the breast drain excess fluid and plasma proteins into lymph nodes. Most of this drainage goes into nodes in the armpit, and the rest goes to nodes located in the middle of the chest.
Breast Density and You
Many states, including California, Virginia, and New York now require radiologists to contact a woman if her breasts are dense. The law is designed to improve breast cancer detection by notifying a woman that mammography may not be as effective for her as other detection tools are. But this doesn’t necessarily mean her risk of cancer is greater.
According to Dr. Carol Lee, a radiologist with Memorial Sloan Kettering, this notification is meant to facilitate communication between a woman and her doctor in order to discuss risk factors that might call for other types of testing.
Breast Density and Cancer Risks
While dense breasts make mammograms harder to interpret,studies also show that women whose breasts are denser have a four to six times greater risk of breast cancer. This has puzzled researchers because these women are typically younger. And breast cancer is more commonly found in older women.
One thought is that women with dense breasts have a higher proportion of ducts and lobes and thus have a higher risk. Cancer arises in the lobes and ducts. But this is uncertain, and researchers are still studying this concept.
What Should a Woman with Dense Breasts Do?
Women should ask their doctors if their breasts are dense and discuss their cancer risks. Those who have a family history or lifestyle risk of cancer may want to explore other testing options like ultrasound or MRI. These tests can sometimes be more helpful than a mammogram in evaluating a woman who has very dense breasts. Women on hormone therapy may want to discuss this with their doctor, as there is evidence that hormones may also increase cancer risk.