The Effect Breast Density Has on Breast Cancer Screenings

If you've recently had a mammogram and were told you have dense breasts, you probably have some questions about what this means and how it affects your breast cancer risks and future exams. While dense breast tissue is common and may never cause additional problems, it can contribute to the need for additional testing in order for your doctor to get an accurate screening for breast cancer.

What Does it Mean to Have Dense Breasts?

Breast density is a term used to describe the types of tissue that make up your breasts. Simply put, dense breasts have more connective and breast (glandular) tissue than fatty tissue. These types of tissues show up differently in the images that are created during a mammogram, making it more challenging for a doctor to determine whether any tumors are present. Because of this, additional screening may be needed for a better view.

What Causes Dense Breasts?

There are a number of factors that may cause dense breast tissue— none of which can be prevented as breast density comes from a combination of your genetic makeup and your age. Breast density can change over time, often becoming less dense the older you get. Some common reasons women have dense breasts include:

• Age: Approximately 50% to 60% of women between the ages of 40 and 44 have dense breasts, while only 20% to 30% of women aged 70-74 have them.
• Weight: About 50% to 60% of women who maintain a healthy weight have dense breasts compared to 20% to 30% of women who are obese.
• Medications: Breast density can be influenced by hormones. Women who take menopausal hormone therapy have more dense breasts than normal because MHT slows the process that makes breasts less dense. Tamoxifen reduces density and is sometimes used for risk reduction.
• Family history: Dense breasts can run in the family.

Breast Density Types

The four categories of breast density range from almost all fatty tissue to very dense tissue with minimal fat. The radiologist who reads your mammogram will determine which category best describes your breasts. These are the four breast density categories:

• Mostly fatty: Breasts are made up of almost all fatty tissue, making abnormalities easy to detect on your mammogram.
• Scattered density: Breasts are composed of mostly fatty tissue, with scattered areas of dense tissue throughout.
• Consistent (heterogeneous) density: The breasts have mostly dense tissue evenly distributed throughout the breasts, which can make it hard to detect small tumors around the dense tissue.
• Extremely dense: Breasts are extremely dense, making mammograms difficult to read since tumors aren't visible around dense tissue.

Your mammogram report will explain the amount of dense tissue found in your breasts. After your images are reviewed by a radiologist, your doctor will discuss the results with you and recommend more tests if necessary.

Breast Density and Breast Cancer: What’s the Connection?

Breast density affects your cancer risk in two main ways. First, dense breasts increase your risk of developing breast cancer. Second, dense breasts increase the difficulty of seeing tumors on traditional screening tests. Additionally, studies have shown that women with dense breast tissue are also more likely to suffer from larger tumors. However, the reasons for cancer risk may not be the same as the cause of large tumors.

Women with a high breast density are four to six times more likely to develop breast cancer than those with mostly fatty breast tissue— and this risk increases with the amount of dense tissue found in your breasts. While the reason for the connection is currently unknown, it's important to remember that breast density is only one of the risk factors related to breast cancer.

Women with dense breasts are also known to have larger more aggressive tumors. Again, this could be simply because the tumors are more difficult to detect. As with other cancers, early detection is key to successful treatment. Therefore, your doctor may suggest you have additional tests if you have extremely dense breast tissue.

How Dense Breasts Affect Your Mammogram

Only a mammogram can determine breast density. On mammogram images, fatty breast tissue appears grey or opaque, while dense or fibrous tissue appears white. While this is an effective way to determine breast density, tumors and other abnormalities also look white on your mammogram. This is why abnormalities are so hard to detect.

Mammograms are still considered the most effective way to screen for breast cancer. The test is performed by a special technologist called a mammographer. When the mammogram is complete, the images are reviewed by a radiologist. After your breast density is determined, your doctor can decide if you need additional tests.

Additional Breast Cancer Screening for Women with Dense Breasts

Your breasts and your personal situation are uniquely your own. Therefore, to ensure that you get the best screening plan, talk with your doctor. Your doctor will consider your risk factors and protective factors that may lower your chance of breast cancer before recommending further tests. Common imaging tests include:

• 3-D Mammography (breast tomosynthesis): Tomosynthesis uses several images to create a 3-D image of the breast instead of the 2-dimensional image created by a traditional mammogram.
• MRI: A breast MRI uses radio waves and strong magnets to create detailed images of the breast. This test may be recommended for women who have already been diagnosed with breast cancer to determine the size of the tumor or as a part of a screening plan for women at high risk for breast cancer.
• Ultrasound: Breast ultrasound uses sound waves to take images of the breast. An ultrasound is a non-invasive test that may be used after an abnormal mammogram.

Remember, dense breasts are only one of many risk factors for breast cancer. If you have questions about breast density or any other questions regarding breast cancer risk factors, make an appointment with your doctor so you can get the answers you need.

Categories: Breast Cancer