Breast density a key factor in cancer screening


Special to The Miami Herald

The next time you have a mammogram, take the opportunity to ask your doctor if you have dense breasts. The answer to this question may help prevent you from being among the nearly 40,000 American women who die of breast cancer each year.

“Knowledge is power when it comes to your health,” says Dr. Cristina Vieira, a radiologist at Baptist Health Breast Center.

When your doctor receives your mammogram report from the radiologist, it provides information about the density of your breasts. The more fibro-glandular tissue you have in your breasts compared to fatty tissue, the denser your breasts.

Remember that breasts are glands that produce milk. They contain lobules that are little sacks where the milk is formed, ducts which transport the milk, and tissue surrounding the glandular structures that give the breast its form and shape. These make up the fibro-glandular portion of your breasts, explains Dr. Monica Yepes, a breast radiologist at the University of Miami Sylvester Comprehensive Cancer Center.

Whenever you have a mammogram, the radiologist reading the X-rays determines the density of your breasts by placing them on a scale of one (least dense) to four (most dense) using the Breast Imaging Reporting and Data System (BI-RADS) of the American College of Radiology.

About half of all women are in categories three and four and therefore have dense breasts. “If you fall into one of these categories, don’t worry, it’s normal,” Yepes says. “It’s just how your body is made up.”

And your breast density can change over your lifetime. Younger women and older women on hormone replacement therapy tend to have more fibro-glandular tissue and denser breasts than others. Also a large weight loss or gain may also affect breast density.

But one thing doctors know for sure is that dense breasts do not increase your risk of dying from breast cancer.

Dr. Mary Hayes, chief of Women’s Imagine for Radiology Associates of Florida, explains that if two patients are identical except one has dense breasts, both women will respond the same way to the same cancer.

“However the trick is to find the cancer in that dense breast tissue,” says Hayes who works at Memorial Healthcare Systems.

When she looks at the film from a mammogram, the fatty breast tissue appears gray or black on the X-ray. Meanwhile, the fibro-glandular tissues as well as many cancers appear white.

“So detecting a cancer among the dense tissue is like looking for a snowball in a snowstorm or the stars in the daytime sky,” Hayes says. “You know the stars are there but it’s much easier to see them against the dark night sky.”

Although mammography is still the gold standard for detecting breast cancers and has reduced the likelihood of dying from breast cancer by 30 percent according to Hayes, it’s not a perfect tool. So for patients with dense breasts in particular, your doctor may recommend further screening.

One option that gained FDA approval in February 2011, is 3-D mammography or tomosynthesis.

The machine looks much like the one used for traditional mammography but instead of taking one picture, it produces an image that resembles the pages of a book. Each “page” represents a one millimeter thickness of your compressed breast.

“If there is any dense breast tissue or other features that are causing the potential cancer to hide, we can unravel them,” Hayes says.

She’s excited that these machines are now available at Memorial Regional Hospital in Hollywood and Memorial Hospital Miramar in Pembroke Pines. By October, they should be available throughout the Memorial Hospital System. There are about 10 tomosynthesis machines already in use from Coral Gables to Delray Beach.

With tomography, Hayes finds that the false positives (the number of times women are recalled to the office to check on something that ends up being benign) are reduced by 20 percent.

However, it won’t replace the traditional mammogram as the two technologies are complementary.

Hayes explains it this way: If you are planning to drive from Florida to Maine, you look at a large map to see what states you’ll pass through. Then, when you get on the road, you consult local maps for detailed driving directions.

In the same way, a mammogram gives doctors a picture of the overall appearance of the breasts that can be compared from year to year. The 3-D image on the other hand lets them “drill down and look millimeter by millimeter, page by page through that breast,” Hayes says.

After you’ve had a mammogram and perhaps tomosynthesis and if you find out you have dense breasts, your doctor can help you determine your next step based on your age, your family and your medical histories.

If your mother had breast cancer and your sister had it in her 30s or 40s or if you had chest radiation at an early age for Hodgkin’s lymphoma, chances are your doctor will prescribe a chest MRI. For other patients with dense breasts who are at lower risk for developing breast cancer, bilateral ultrasound is often the preferred follow-up to a mammogram. Ultrasound has proven to uncover three to four additional cancers for every 1,000 women screened, according to Yepes.

But the downside to ultrasounds as well as MRIs is that although they detect a multitude of irregularities, they are not very good at showing if these are malignant or benign. This can result in the patient having to go through more follow ups, tests and biopsies.

“It is a balancing act for the patient and the doctor to decide and can get difficult,” Yepes says.

Women are starting groups such as How Dense Are you ( They are working to pass state and federal legislation requiring that women be given more information about dense breasts in the letter telling them the results of their mammograms.

Almost a dozen states have enacted such laws. Florida had a bill pending but concern about wording from the medical community kept it from gaining momentum and it died.

However, there’s really no need for legislation if you take responsibility for your own health. Initiate that conversation about breast density with your doctor.

“Together we can weigh the pros and cons,” Yepes says.

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