Breast Density

Dense breast tissue: What it means to have dense breasts

Dense breast tissue is detected on a mammogram. Additional imaging tests are sometimes recommended for women with dense breasts.

If a recent mammogram showed you have dense breast tissue, you may wonder what this means for your breast cancer risk. Doctors know dense breast tissue makes breast cancer screening more difficult and it increases the risk of breast cancer.

Review your breast cancer risk factors with your doctor and consider your options for additional breast cancer screening tests. Together you can decide whether additional screening tests are right for you.

mammogram

What is mammography?

Mammography is the screening test that is used to find early breast cancer.

Mammography uses low-energy X-rays to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses or microcalcifications.

More recently, it has been determined that the overall “density” of the background image of the breast is an indicator of future breast cancer. This background density or whiteness varies from woman-to-woman and changes during a women’s life.

What is dense breast tissue? How is breast density determined?

Dense breast tissue refers to the appearance of breast tissue on a mammogram. It’s a normal and frequent finding.

Breast tissue is composed of glands that make milk during breast feeding, ducts that conduct milk to the nipple, and supportive tissue (dense breast tissue), and fatty tissue (nondense breast tissue).

Dense breast tissue is whiter on a mammogram which makes it difficult to see through. Fatty tissue is grayer on a mammogram.

When viewed on a mammogram, women with dense breasts have more dense tissue than fatty tissue.

Breast density

What causes dense breast tissue?

The normal breast (right) contains the yellow “stroma” that surrounds the milk-making tissues (here, purple) of the breast. The microscopic image at the bottom shows the two tissues of the stroma: the “dense” pink fibrous tissue and the “non-dense” clear, open fatty tissue.

It’s not clear why some women have a lot of dense breast tissue and others do not.

You may be more likely to have dense breasts if you:

Are younger. Your breast tissue tends to become less dense as you age, though some women may have dense breast tissue at any age.

Have a lower body mass index. Women with less body fat are more likely to have more dense breast tissue compared with women who are obese.

Take hormone therapy for menopause. Women who take combination hormone therapy to relieve signs and symptoms of menopause are more likely to have dense breasts.

The normal breast (below) contains the yellow “stroma” that surrounds the milk-making tissues (here, purple) of the breast. The microscopic image at the bottom shows the two tissues of the stroma: the “dense” pink fibrous tissue and the “non-dense” clear, open fatty tissue.

It’s not clear why some women have a lot of dense breast tissue and others do not.

You may be more likely to have dense breasts if you:

Are younger. Your breast tissue tends to become less dense as you age, though some women may have dense breast tissue at any age.

Have a lower body mass index. Women with less body fat are more likely to have more dense breast tissue compared with women who are obese.

Take hormone therapy for menopause. Women who take combination hormone therapy to relieve signs and symptoms of menopause are more likely to have dense breasts.

Why does breast density matter?

Having dense breasts affects you in two ways:

Increases the chance that breast cancer may go undetected by a mammogram, since dense breast tissue can mask a potential cancer

Increases your risk of breast cancer, though doctors aren’t certain why.

The images to the right show the four levels of density, called BI-RADS A, B, C, D and the appearance of a cancer in each backgrounds. Notice how the cancer in the far right image is getting hard to see. Women with dense breasts make up 50% of all women.

Having dense breasts affects you in two ways:

Increases the chance that breast cancer may go undetected by a mammogram, since dense breast tissue can mask a potential cancer

Increases your risk of breast cancer, though doctors aren’t certain why.

The images below show the four levels of density, called BI-RADS A, B, C, D and the appearance of a cancer in each backgrounds. Notice how the cancer in the far right image is getting hard to see. Women with dense breasts make up 50% of all women.

breast density

What tests are recommended for breast cancer screening?

Most medical organizations recommend women with an average risk of breast cancer consider regular mammogram testing beginning at age 40 and consider repeating the screening annually.

Women with dense breasts, but no other risk factors for breast cancer, are considered to have a higher risk of breast cancer than average. They may benefit from annual breast cancer screening.

Dense breast tissue makes it more difficult to interpret a mammogram, since cancer and dense breast tissue both appear white on a mammogram. Very dense breasts may increase the risk that cancer won’t be detected on a mammogram.

Despite concerns about detecting cancer in dense breasts, mammograms are still effective screening tools. The most common type of mammogram — digital mammogram — saves images of your breasts as digital files instead of film and allows for more detailed analysis. This is more effective at finding cancer in dense breast tissue than older film mammogram technology.