How Does Breast Density Affect Your Breast Health?

What Breast Density Means for Your Health

You recently had a mammogram and your report said something you didn’t expect: Dense breasts. Or maybe you haven’t had your first mammogram yet and you’re wondering if you’re among the roughly 50% of women who fall into that category.

High breast density is normal and common among women, but it could impact your breast cancer risk. It’s important to know what dense breasts do – and don’t – mean so you can best manage your individual risk profile.

What Exactly Are Dense Breasts?

Human breasts are complex organs consisting of glands, ducts and connective tissue, which includes fibrous and fatty tissue. Different breasts have different balances of these anatomical structures; dense breasts are those with more glandular than fatty tissue.

Radiologists determine breast density using the American College of Radiology's Breast Imaging Reporting and Data System, or BI-RADS, classification system.

The different categories of breast density are as follows:

• Category A: Breasts in this category are composed almost entirely of fatty tissue.
• Category B: Breasts in this category have some areas of dense tissue but are still primarily composed of fatty tissue. Category-B breasts are considered non-dense.
• Category C: Breasts in this category have higher concentrations of dense tissue, roughly equal to fatty tissue. Category-C breasts are considered dense.
• Category D: Breasts in this category are composed almost entirely of dense tissue.

Breast density tends to be higher in younger women, usually decreasing as you age. There is, however, a strong genetic component; if your mother or grandmother has dense breasts, you are more likely to as well.

A mammography is the only way to determine if you have dense breasts. Since 2024, the Food & Drug Administration has required doctors to inform their patients if their mammography indicates they have dense breasts.

How Does Breast Density Impact Cancer Risk?

Dense breasts are not a health condition or a medical diagnosis. It is a normal anatomical observation affecting roughly half of women over 40.

However, breast density does impact your cancer risk; those with dense breasts have a higher likelihood of contracting breast cancer. It isn’t clear right now why that is the case, but it may be related to the higher prevalence of cells that could become cancerous. (It’s important to note, however, that women with dense breasts are not more likely to die from breast cancer.)

False-negative mammograms are also more common in women with dense breasts, which could affect cancer risk. Tumors appear white on a breast scan, which is the same color as healthy glands and tissue, so if a tumor is hiding in a particularly dense area of the breast, it could be missed.

What Can You Do to Manage Your Cancer Risk?

Don’t be alarmed if your provider informs you that you have dense breasts; density is just one of many factors that influences your cancer risk. Other risk factors include:

• Age (women over 50 are more likely to get breast cancer)
• Family and personal history of breast cancer
• Genetic predisposition
• Past radiation therapy exposure
• Reproductive history

Your care provider will work with you to explore all of the above factors, including your breast density, to build a complete understanding of your individual risk profile. This will help them determine if additional testing is appropriate.

Breast magnetic resonant imaging (MRI) may be recommended if it is determined you are higher than average risk (not simply if you have dense breast tissue). This will provide a more thorough examination of your breasts. Your provider may also recommend you receive more frequent screenings.

Additional screening is not always beneficial, however. More tests naturally lead to more false-positives, which could create unnecessary costs and stress as you undergo even further testing. That’s why it’s important to have a conservation with your care provider to determine what makes sense in your case.

Dense breasts aren’t something to be overly worried about; with proper planning and risk management, you can ensure you’re receiving the attention and screening you need to take care of your breast health.