How Breast Density Affects You

In celebration of Breast Cancer Awareness Month, we are sharing important information you should know about breast density. We are required to include information identifying your breast tissue density in your mammogram report. Just like your blood pressure and your body weight, breast density is an important thing for women to know. Here’s why:

The Basics

• Breasts are made up of four different parts: milk glands, milk ducts, connective tissue, and fat. Breast that contain a lot of fat are penetrable or light. They are easy to see through during a mammogram. Fibrous connective tissue is dense. Women with more connective tissue are said to have dense breasts. 
• Dense breast tissue is completely normal and not a concern in and of itself. And there are not many behavioral causes, apart from some forms of hormone therapy, which does increase breast density. Dense breasts are inherited, mostly. Although Asian women are more likely to have dense breasts, breast density affects women of all races.
• Breast density does decrease with age. More than half of women under age 50 have dense breasts, while only 40 percent of women in their 50s and only 25 percent 60 and older do. 
• You might guess if your breasts are firm that they are dense. But that is not always the case. Breast density cannot be detected by how your breasts look or feel. It is not linked to firmness or size. The only way to tell if you have dense breasts is by having a mammogram. At the same time your radiologist looks for abnormal areas, he or she will also evaluate breast density.
• Your radiologist will assign density to your breasts. The density descriptions were created by the American College of Radiology as a part of their Breast Imaging Reporting and Data System. There are four types: least dense, scattered, more dense, and densest.

Women who have dense breasts are at a slightly higher risk of developing breast cancer.
More than half of all women who develop breast cancer have no additional risk factors other than being female and aging; however, dense breast tissue can increase your risk of getting breast cancer. As density increases, risk increases. Women with the densest breasts have a risk for breast cancer that is 4- to 6-times higher than that of women with the least dense breasts.

In addition, the character of dense breast tissue makes breast cancer harder to find.
On a mammography reading, fat appears almost black. Fibrous tissue shows up white. One of the main problems with high breast density is that cancer also appears white. So, if a woman has a lot of fibrous tissue, the radiologist reading the test may find it difficult to detect cancer.

Knowing your risk of breast cancer, including breast density, can help you make good decisions regarding prevention and screening.
For most women, no additional screening will be recommended. Depending on your age, other risks, and your breast density, your provider may recommend an additional screening, like ultrasound or MRI. While combining screening methods does increase the likelihood of finding cancers, it also increases the number of false positives, including perhaps unnecessary biopsies. That’s why it is wise to consider additional testing with your provider.

The website densebreast-info.org is an excellent resource for answers to more common breast density questions and helpful screening images that make it easy to see the differences between breasts of different densities.

Dr. James Keenan is a radiologist with Radiology Associates of Bennington. The group provides radiology services to Southwestern Vermont Medical Center in Bennington.