On Your Health

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What You Should Know About Dense Breast Tissue

If you’ve been told you have dense breasts, don’t worry. Your breasts are as normal as everyone else’s.

Roughly 40 percent of women of mammography age have dense breasts. Women in their 40s are more likely to have dense breasts while 40 percent of women in their 50s have them.

The percentage goes down with age with just under 30 percent of women in their 60s and 25 percent in their 70s having dense breast tissue. While having dense breasts is normal, it does pose challenges, especially in detecting breast cancer.

On November 1, 2019, a new law took effect in Oklahoma requiring women to be notified if they have dense breast tissue and what additional testing may be required. Senate Bill 443, known as Nancy’s Law, is named for Nancy Simpson of Edmond, who died in 2018. She died from stage four breast cancer despite her mammograms being clean for several years.

Simpson had dense breast tissue, and the law aims to inform women that additional imaging may be needed because of the challenges of detecting cancer with a 2-D mammogram.

Here is what you need to know about breast density and how it affects you.

What does dense breast tissue mean?

When you’re told you have dense breast tissue, it usually refers to the appearance of the breast tissue on mammograms.

“The breasts are composed of breast tissue and fat. This breast tissue is termed fibroglandular tissue and comprised of milk ducts, glands, and supportive tissue,” said Dr. Zachary Redus, a board certified radiologist at INTEGRIS Southwest Breast Health and Imaging Center. “Breast density is a term used that assesses how much fibroglandular tissue there is relative to fat. Someone characterized as having dense breast tissue has a greater amount of fibroglandular tissue when compared to the amount of fat tissue on the mammograms.”

While it’s not entirely understood why some women have dense breast tissue and others do not, some factors include being a younger age, hormone replacement in postmenopausal status and low body mass index.

How does dense breast tissue affect mammograms?

Breast density is not based on how the breasts “feel” during a self-breast examination or by a clinical breast examination from your doctor. Only mammography can determine if you have dense breasts based on the amount of fibroglandular tissue and fatty breast tissue.

“Mammograms with dense breast tissue are more difficult to read than mammograms with non-dense ‘fatty’ breast tissue,” said Dr. Redus. “This is because dense breast tissue on mammography appears white as do masses. So one could imagine, having dense breast tissue on mammography may obscure a tiny mass until it increases in size to which it becomes detectable. Having dense breasts also causes a slight increased risk for developing breast cancer when compared to an individual considered to have fatty tissue.”

How can women care for their health with dense breasts?

As always, women should get their annual screening mammography. Women with an average risk for developing breast cancer should begin annual screening mammography at the age of 40. 

Women with dense breasts should consider 3-D mammography, which takes multiple images through the breasts. This allows the radiologist to scan through the tissue and possibly detect a small cancer that may otherwise be obscured by overlapping dense tissue on a standard 2-D digital mammogram study.

“Other imaging modalities, to include ultrasound and MRI, can be used as additional screening to supplement the mammograms in someone considered to have dense breast tissue, but does not take the place of the annual mammograms,” said Dr. Redus.

The need for additional screening using these other options is usually decided on an individual basis after reviewing the patient's risk factors and personal preferences. According to Dr. Redus, women with dense breasts can also protect their health with:

    1. Monthly self-breast examinations and yearly clinical breast examinations performed by a physician.
    2. Lifestyle choices such as maintaining low body fat, exercising, not smoking, limiting alcohol consumption, and eating a balanced diet.

Breasts tend to become less dense with age and after menopause as the glandular tissue shrinks.

The bottom line about dense breast tissue

Nearly 20 percent of cancers are missed in mammography, and that rises to 40 to 50 percent in women with dense breasts. Digital and 3-D mammograms are more effective in detecting cancer in dense breasts, so be sure to ask your doctor about the options.