What Is Dense Breast Tissue, and How Does It Relate to Breast Cancer?


While getting a mammogram is a good way to detect the possibility of breast cancer, it can also detect something else: dense breast tissue. In fact, dense breast tissue is a finding exclusive to a mammogram, wherein certain parts of the breast appear brighter than others in the resultant x-ray image. It can look light gray or white, and may make it harder to detect any present abnormalities. 

Additionally, studies have found that there is "at least a moderate association of mammographic breast density and the risk of breast cancer." But what else should you know about dense breast tissue, and how do you properly screen for breast cancer if you have it? Read on to learn more.

What-Is-Dense-Breast-Tissue-GettyImages-962179310 What-Is-Dense-Breast-Tissue-GettyImages-962179310 of fatty tissue, fibrous tissue, and glandular tissue (also known as ducts and lobules). The fibrous tissue helps to hold the breast in place while the glandular tissues are what produce and store breast milk. Interspersed within these structures is the fatty tissue. The fibrous and glandular tissues are collectively referred to as dense tissue, and those with dense breasts have more of these two kinds in relation to the amount of fatty tissue present. 

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Anita Johnson MD, FACS, breast cancer surgical oncologist at the Cancer Treatment Centers of America, says that dense breast tissue is "tissue on the mammogram that is hard to see." In order to assess mammographic density (the term commonly used to describe the percentage of dense tissue in the breasts), clinicians will look at a patient's mammogram and use breast imaging reporting and data systems (BI-RADS). Mammographic density is scored on a range from 1 to 4, wherein an mammographic density of level 1 indicates that the breast is composed almost completely of fatty tissue and level 4 describes breasts with 75% or more of the tissue present being dense tissue. 

A higher mammographic breast density is associated with a higher risk of breast cancer in two ways. First, it can reduce the sensitivity of a mammogram, potentially obstructing abnormalities. Second, it has been found to be an independent risk factor for development of breast cancer, and studies have shown a positive correlation between higher mammographic density and incidents of breast cancer. Studies have also shown that those with higher breast density are more likely to have interval cancer (cancer that presents because of symptoms during the time between regular screening), so it's important to make regular screening appointments.

Who is most likely to have it?

Higher mammographic breast density is dependent on a number of factors, including race and diet (diets that are rich in red meat, bread, dairy, and alcohol, for example, are associated with a higher mammographic density level). Studies have also shown that it's commonly associated with genetics and has a high heritability. Another important factor is age. Susan Brown, MS, RN, and director of the health information center at Susan Komen tells Health that findings of a high breast density is more common for those ages 44 and younger who have gotten mammograms (many don't start getting mammograms until the age of 40). "As one ages, their breast density is lowered," she says. However, those who are post-menopausal and taking estrogen and progestin have also been found to be at increased risk, though this study states that only taking estrogen (without progestin) may not be associated with increased breast density. 

What do you do if you have it?

According to Dr. Johnson, dense breast tissue is not something you can get rid of, and she also explains that not everyone who has it will develop cancer. It is advised that patients who are at risk and those who are above the age of 40 get their routine mammograms. Since breast density has the capability to obscure tumors, mammogram centers are now obligated by an FDA proposal to inform patients of their findings.

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Knowing if you have a higher mammographic density is important, as Dr. Johnson advises being proactive and making an appointment with your provider to talk about a plan of action. "Know your family history, talk to your primary physicians about additional imaging," she says. This is especially important, given the higher risk associated with interval cancers.

How does one properly screen for breast cancer when you have dense breast tissue?

Brown mentions that this is still an area of research. "There are no guidelines on what to do with the information on increased breast density. There are currently studies looking at whether 3-D mammography is better than 2-D in saving lives. But in most cases, ultrasound, and breast MRI are recommended to further assess the situation," she explains. Dr. Johnson advises talking with your physician about additional imaging, perhaps especially if there's a family history of cancer.

She also reminds us of the bottom line, which is that early detection matters. While several guidelines mention that the decision to start getting regular mammograms between the ages of 40 to 49 is a personal choice, Dr. Johnson advises making an appointment, especially if you are at an increased risk. 

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