Dense Breast Tissue

What is dense breast tissue?

Dense breast tissue is when your breasts have more fibrous and glandular tissue and less fatty tissue. It’s common — about 50% of people assigned female at birth (AFAB) have dense breast tissue.

Dense breast tissue doesn’t cause symptoms. It doesn’t make your breasts hurt or change what they look like. You won’t feel any change in your breasts when you do a self-breast examination, or a healthcare provider checks your breasts.

Providers don’t do tests to diagnose dense breast tissue. Typically, you learn you have dense breast tissue if you have a 3D mammogram (digital breast tomosynthesis). Your mammogram report will state if your breast tissue is dense or not dense.

Dense breast tissue makes it more difficult for a radiologist to detect breast cancer because both tumors and dense breast tissue appear white on a mammogram. You may have higher risk of developing breast cancer if you have extremely dense breast tissue.

Learning that your breast tissue is denser than is typical may surprise you. Having dense breast tissue isn’t a cause for alarm. But it is a reason to ask a healthcare provider to explain your mammogram results. They may use terms like breast density or fibroglandular density when they talk about dense breast tissue.

Types of breast tissue

To understand dense breast tissue, it may help to know more about your breast tissues. There are three types of breast tissue:

• Fatty tissue: Fatty tissue (adipose tissue) isn’t dense. It appears dark or see-through on a mammogram. That makes it easier for a radiologist to spot white areas that could be cancer.
• Fibrous connective tissue: This dense tissue supports, protects and holds your muscles and tissues in place. It appears white on a mammogram.
• Fibroglandular tissue: This tissue consists of the glands that make breast (chest) milk and the ducts that carry milk to your nipples. Like fibrous connective tissue, this tissue is dense and appears white on a mammogram.

Levels of dense breast tissue

Radiologists use the Breast Imaging Reporting and Data System (BI-RAD) to classify dense breast tissue. This data system puts breast tissue into four categories. The categories range from having very little dense tissue to having extremely dense tissue. The four categories are:

What causes dense breast tissue?

There’s no single cause for dense breast tissue. Risk factors include your:

• Age: Your breasts are naturally denser when you’re in your 20s or 30s. As you grow older, your breasts become less dense.
• Body weight: People with a low body mass index (BMI) may be more likely to have dense breast tissue.
• Family history: Breast density may be genetic, which means you may have a similar density as your biological family.
• Medication: Treatments like hormone replacement therapy may change your breast density.

What is the treatment for dense breast tissue?

There isn’t a medication or procedure to reduce the amount of fibrous and fibroglandular tissue in your breasts.

If a mammogram shows you have dense breast tissue, a healthcare provider may do a breast cancer risk assessment. This tool predicts the likelihood that you’ll have breast cancer during your lifetime

Your provider may use assessment results and your mammogram results to order additional imaging tests, including:

• Breast MRI: In a breast MRI (magnetic resonance imaging), a magnet, radio waves and a computer produce detailed images of breast tissue.
• Breast ultrasound: Ultrasound uses sound waves to create pictures of your breast tissue.
• Molecular breast imaging (MBI): Molecular breast imaging (MBI) is a breast imaging test that uses a radioactive tracer and special scanning equipment. This test highlights cancerous cells even in dense breast tissue, where cancer can be harder to spot.

Can dense breast tissue turn into cancer?

No, it can’t. Breast cancer happens when breast cells mutate and become cancerous cells. That can happen if your breasts are fatty or dense. But having extremely dense breast tissue increases your breast cancer risk. That’s because breast cancer often starts in your fibroglandular tissue, a type of dense breast tissue. The more fibroglandular tissue that you have in your breast, the greater the chance you’ll develop breast cancer.