What is scattered fibroglandular breast tissue?

Scattered fibroglandular tissue refers to the density and composition of your breasts. A woman with scattered fibroglandular breast tissue has breasts made up mostly of non-dense tissue with some areas of dense tissue. About 40 percent of women have this type of breast tissue.

Breast tissue density is detected during a screening mammogram. A physical examination isn’t able to accurately determine your breast tissue density. Only an imaging test can do that.

What results should I expect from a mammogram?

During a mammogram, your radiologist will look for unusual lesions or spots that may indicate cancer. They will also examine your breast tissue and identify different characteristics of the tissue, including density.

A mammogram will show several types of breast tissue:

  • Fibrous tissue, also called connective tissue, appears white on mammograms. This type of tissue is difficult to see through. Tumors can hide behind this tissue.
  • Glandular tissue, which includes milk ducts and lobules, appears white on a mammogram. It’s also difficult to see through, which means lesions or questionable spots may be difficult to detect in this tissue.
  • Fat is easy for a mammogram to penetrate, so it will appear see-through or translucent on the scan.

Breast tissue density is then divided into four categories. Each of these categories is determined by the ratio of dense (opaque) tissue to fat (translucent).

In order of least to most dense, these breast tissue categories are:

  1. Fatty breasts. If your breasts are composed almost entirely of non-dense fat, they’re considered fatty breasts.
  2. Scattered fibroglandular breast tissue. This category includes breasts that have areas of dense tissue, but have a higher ratio of non-dense fat.
  3. Heterogeneous density. For this category, the breast includes non-dense fat, but more than half of the tissue in the breast is dense.
  4. Extreme density. When most of the tissue in your breast is dense, the density is considered “extreme.” Dense breasts can be 6 times more likely to develop breast cancer. Extreme density also makes it harder for mammograms to detect breast cancer.

It’s unclear why some women have one type of breast density over another, and how a woman develops the type of breast tissue she has.

Hormones may play a role. Exposure to hormones, fluctuating hormone levels, and medications that contain hormones, such as birth control, may change a woman’s breast tissue density ratio. For example, breast tissue becomes less dense during menopause.

This coincides with a decrease in estrogen levels. Doctors don’t believe women can do anything to actively alter their density ratio, however.

Some risk factors increase a woman’s chances for dense tissue:

  • Age. Breast tissue tends to become less dense with age. Women ages 40 to 50 usually have higher breast tissue density than women over age 60.
  • Medication. Women taking certain hormonal medications may increase their risk for dense tissue. This can be true for women who use hormonal replacement therapy to ease the symptoms of menopause.
  • Menopause status. Women who are premenopausal often have greater breast density than women who are postmenopausal.
  • Family history. Breast density appears to run in families, so you may be genetically predisposed to having dense breasts. Ask your mother and other women in your family to share their mammogram results.

The only accurate way to measure and diagnose breast density is with a mammogram.

Some states require doctors to tell you if you have dense breasts. The idea behind these laws is to help women understand the additional measures they may need to take to help detect breast cancer.

Dense breast tissue can complicate a breast cancer diagnosis. Finding tumors among the dense breast tissue can be difficult. Additionally, women with dense breast tissue have an increased risk for breast cancer compared with women whose breast tissue is less dense.

Instead of trying to alter breast tissue density, doctors and medical researchers are focused on encouraging women to find out what type of breast density they have and what to do with that information.

Women who have dense breast tissue, either heterogeneously dense or extremely dense, in addition to other risk factors for breast cancer may need additional breast cancer screening tests. A simple mammogram alone may not be enough.

These additional screening tests may include:

  • 3-D mammogram. While your radiologist is performing a regular mammogram, they may also perform a 3-D mammogram, or breast tomosynthesis. This imaging test takes pictures of your breast from several angles. A computer combines them to form a 3-D image of your breast.
  • MRI. An MRI is an imaging test that uses magnets, not radiation, to see into your tissue. This test is recommended for women with dense breasts who also have an increased risk of breast cancer based on other factors, such as genetic mutations.
  • Ultrasound. An ultrasound uses sound waves to see into dense breast tissue. This type of imaging test is also used to investigate any areas of concern in the breast.

It’s important to know what type of breast tissue density you have. Scattered fibroglandular breast tissue is common. In fact, 40 percent of women have this type of breast tissue density.

Women with scattered fibroglandular breast tissue density may have areas of breast tissue that are denser and difficult to read in a mammogram. For the most part, however, radiologists will not have many issues seeing possible areas of concern in this kind of breast.

Talk to your doctor about when to start regular screenings.

If you’re a woman at average risk for breast cancer, then the American College of Physicians (ACP) recommends that you:

  • discuss your mammogram preferences with your doctor if you’re in your 40s; the risk of mammograms may outweigh the benefits
  • get mammograms every other year if you’re between 50 and 74 years old
  • stop receiving mammograms once you’re 75 years old or have a life expectancy of 10 years or less

However, the American Cancer Society (ACS) recommends that women of average risk have the option of beginning annual screening at 40 years old. If they don’t begin annual mammograms at 40 years old, then they should start annual screening at 45 years old. They should switch to mammograms every other year once they’re 55 years old.

Regular screening allows doctors to see changes over time, which can help them identify any areas of concern. It may also provide an opportunity for doctors to catch cancer early before it’s had a chance to advance.

If you don’t know your breast tissue density, ask your doctor about it at your next visit or before your next mammogram. After the mammogram, use these questions to help spark the conversation:

  • What type of breast tissue do I have?
  • Do I have dense breast tissue?
  • How does my breast tissue affect my mammogram and breast cancer screening?
  • Should I have additional screenings beyond the mammogram?
  • Are my risks for breast cancer higher because of my breast tissue type?
  • Is there anything I can do to reduce the percentage of dense breast tissue?
  • Am I on any medications that might affect the percentage of dense tissue?

The more you know about your risks, the more proactive you can be about taking care of your body. By far, the best way to approach breast cancer is to find it early and begin treatment right away. Mammograms and imaging tests can help you do that.

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