Dense Breasts

On August 8, California women were asked the question: “Are you dense?” The public health awareness event signifies the latest movement in early detection of breast cancer. Studies carried out here in Santa Barbara as well as the rest of the country have shown that women with dense breast tissue (DBT) have a tumor detection rate of only 25 percent when using mammography alone. “Are you dense?” Day calls attention to the fact that while 40 percent of women have DBT, most women have no idea whether they have it or not.

The kind of personal breast exam that women are encouraged to perform every month is not sufficient to figure out one’s density, according to Santa Barbara radiologist Judy Dean. This breast “density” refers to the way tissue appears on a mammogram. Dense breast tissue and cancer cells both show up as white on a mammogram, which makes cancer very difficult to detect if there is a background of dense tissue. Dense breast tissue is mostly glandular tissue rather than fatty tissue. Glandular tissue is where cancerous tumors form, which is why women with dense breast tissue have an increased risk of developing breast cancer.

“Women with this extra risk also have an enormously higher risk of cancer escaping detection by mammography,” said Dr. Dean. “This doesn’t mean mammography isn’t good, it just isn’t good enough for women with dense breast tissue. Micro calcifications are shown best on mammography, and half of breast cancers form micro calcifications. If a cancer doesn’t have calcifications, though, you may not see it on your mammogram if you have dense breast tissue.”

Dean is one of the major forces behind the movement to make women aware of their breast density. In a study started in 2005, she screened 3,000 patients for breast cancer using mammography and ultrasound technology. Mammograms detected tumors in 23 patients, but when secondary ultrasound screenings were added, 23 more women were diagnosed. This second group of women’s mammograms had produced false negatives, and every year an estimated 45,000 women with invasive breast cancer receive false negatives as well. The results of this study were corroborated by a study by the American College of Radiology Imaging Network (ACRIN) published in the Journal of the American Medical Association.

Verlinda Richardson is one of 30 of Dean’s patients whose cancer was not visible on her mammogram and only detected after secondary screenings. Richardson had been aware of the fact that she had dense breasts from a young age and followed Dean’s advice to have an ultrasound to screen for cancer. The ultrasound showed an irregularity, and an MRI uncovered an 8 mm cancerous tumor. A tumor 2 mm larger would have required chemotherapy, but the early detection meant she only needed surgery and radiation therapy.

“I’m very fortunate that I had the MRI done,” said Richardson. “Not only did it save my life, but it actually cost less because we caught it early.”

Dean has gone on to push for legislation in California that would make it mandatory for radiologists to inform women if they have dense breast tissue. The bill (SB 791) was introduced in 2011 by Sen. Joe Simitian but was vetoed by Gov. Brown in October. Reintroduced as SB 1538 with 50 cosponsors, the bill passed unanimously in the State Senate and now awaits review by the State Assembly. Connecticut, Texas, and Virginia have already passed similar notification laws. Dean, who has been informing her patients of their breast density since the 2005 study, has testified before the State Assembly in favor of passing the bill.

“If Dr. Dean hadn’t called me that day,” said Richardson, “I wouldn’t have gone in for the MRI … for a doctor not to tell a woman they had dense breast tissue would be a crime.”

The authors of the ACRIN study attribute the lack of widespread ultrasound screenings to a limited supply of qualified people to conduct the imaging as well as a lack of equipment. It reported that as of 2005, only 35 percent of facilities in the sample population offered ultrasound screenings.

According to Dean, SB 1538 does not propose additional spending. Rather, it would seek to supply women with information that they can use to pursue further screenings if they choose. Some physicians elect to inform their patients of their breast density, but as of now it is not mandatory to do so.

“Every woman gets a required letter after they have a mammogram,” said Dean. “All the legislation proposes is to put information that already goes to women’s doctors into the letters that go to women. Why should women not get that information, too?”

“It’s information that could be lifesaving,” says Dean, “and most women don’t know to ask.”

More information can be found at www.areyoudense.org.