What Is It?
The breast’s primary purpose is to secrete milk to feed infants, this is achieved by the presence of glandular tissue whose role it is to produce and transport milk to the nipple. Along with the glandular tissue, the breast also consists of fibrous tissues, ligaments and fat. Because of their properties when x-rayed, all non-fat tissue is often termed “dense” tissue.
A breast’s density is the percentage of the breast which is dense tissue; a denser breast has a higher percentage of dense tissue than a fatty breast.
Breast density changes throughout a woman’s life with most studies showing breast density decreasing with age, but it is also known to be influenced by other factors such as genetics, body mass index, monthly hormonal cycles, age at first childbirth, and use of post-menopausal hormone replacement.
In a mammogram (a breast x-ray), dense tissue appears white and fatty tissue appears black:
These next mammograms show the variations in breast density possible within a population, from fatty on the left, through extremely dense on the right:
Having dense breasts is not unusual and does not mean that you have any form of disease. You should discuss any concerns you may have about your breast density with your physician.