Many women know that screening for breast cancer is an incredibly important aspect of women's health. But sometimes an annual mammogram isn't enough, especially for those with dense breast tissue.
What is Dense Breast Tissue and Why Does it Matter?
Breast density matters. Here’s why. When you have dense breast tissue, your risk for breast cancer goes up by 4-6 times. And on top of that, cancer in dense breast tissue is much harder to find on a mammogram.
So what is breast density? Breast density is a measurement of the amount of connective, or fibroglandular tissue, as compared to fatty tissue in your breasts.
The more fibroglandular tissue you have, the denser your breasts. When a radiologist reads your mammogram, she defines your breast density as being one of four categories. Those categories rank your density, A - D:
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Predominantly fatty (only 0-25% fibroglandular tissue)
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Scattered fibroglandular density (25-50% fibroglandular tissue)
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Heterogeneously dense (50-75% fibroglandular tissue)
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Extremely dense (greater than 75% fibroglandular tissue)
This system is important because it helps radiologists determine whether a patient requires additional evaluation. About 50 percent of US women over age 40 have dense breast tissue. Younger, pre-menopausal women tend to have denser breast tissue. So how do you know if you have dense breast tissue? You cannot tell by looking at or feeling them - you need a mammogram to determine your density.
Dense breast tissue makes it harder to see small, early breast cancers on a mammogram. This is because fibroglandular tissue and breast cancer both look white on a mammogram. In addition, women with heterogeneously dense or extremely dense breasts have a higher risk of developing breast cancer than women with predominantly fatty or scattered fibroglandular tissue. As I mentioned before, women with dense breasts are 4-6 times more likely to develop breast cancer than women with breasts that are predominantly fatty or have scattered fibroglandular density.
Women who are at intermediate risk or high risk, based on their breast density, should use breast ultrasound as an additional tool in screening for breast cancer. This is especially important because up to 50 percent of cancers in women with higher densities are hidden on mammograms.
Mammogram vs. Ultrasound
It is still critical for all women over age 40 to get annual mammograms - regardless of their density. Why? Because mammograms are still the gold-standard screening tool for women over 40 and are good at picking up micro-calcifications, often an early sign of breast cancer.
So Why Have An Ultrasound After a Mammogram?
Breast ultrasound is particularly effective for women with dense breasts. Ultrasound is quick, painless, and reliable. On an ultrasound, cancer shows up as white, and dense breast tissue shows up as black. Imaging centers may use hand-held or automated breast ultrasounds. An automated breast ultrasound takes hundreds of images of your entire breast. These images are then reconstructed into a 3D image. This provides a picture of the entire breast, rather than a smaller area. Having a 3D image set allows radiologists to look at the images from many different angles to accurately diagnose any abnormality.
If the radiologist sees anything suspicious and decides that additional imaging is needed, the radiologist will report that the exam is incomplete and ask the patient to have additional handheld ultrasound imaging of the area in question. The handheld ultrasound images can help radiologists determine whether the suspicious area is benign (usually a cyst) or whether it needs further evaluation with a biopsy. Keep in mind that 80 percent of biopsy results are benign as well, so a biopsy does not mean that you have breast cancer.
Find Out if You Have Dense Breasts
To ensure that you are getting the best possible care, ask your doctor whether you have dense breast tissue. If you do, request a breast ultrasound in addition to your annual mammogram, as this exam can help detect small breast cancers that would not otherwise be seen on a mammogram.
In short, a screening breast ultrasound could save your life by showing a small, curable cancer rather than waiting until it is larger and less curable.
[1] Screening breast ultrasound can also be referred to as automated breast ultrasound (ABUS), whole breast ultrasound, or 3D breast ultrasound.
This article was first authored by Dr. Thomas on November 15, 2016 during her Brem Fellowship at the George Washington Comprehensive Breast Center. Currently a board-certified physician at XXXX, Dr. Thomas decided to specialize in breast imaging and intervention after seeing the amazing impact that early detection can have, The text of the article was updated in July of 2021 by Brem Foundation staff.
Photo by Victoria Strukovskaya on Unsplash
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