Getting smart about dense breast tissue
Above image: four level breast density scale
By Laura Drucker
Chiqeeta Jameson woke up with a start one morning in 1998. “I have breast cancer,” the 41-year-old announced to her sleeping fiancé. “Are you talking about that lump on your right breast?” he asked, without opening his eyes. Jameson’s declaration “was just some instinctual thing,” she says. But she felt the side of her right breast, and there it was—a small, hard lump.
Despite a palpable lump and a family history of breast cancer (her sister had been diagnosed at age 51), it would take eight months, four doctors and three negative mammograms before Jameson’s fear was confirmed. A 1.7-centimeter invasive ductal carcinoma was inside her breast, dangerously close to spreading into her lymph nodes. “The first thing I felt was complete relief,” Jameson says. “And then I got really upset. I said, ‘I don’t understand this. I did everything I could do. If mammography is supposed to be that good, why didn’t it show the cancer?’”
Jameson has what is referred to as dense breast tissue. Breasts are composed of fatty tissue and fibroglandular tissue. The proportion of each dictates the overall density of a woman’s breasts and, therefore, what can be seen on a mammogram.
“Fat is our friend on the mammogram,” says radiologist Sharmishtha Jayachandran, MD, medical director of the Breast Health Center at Northwestern Medicine Delnor Hospital in Geneva. “[With fatty breasts] we can see through structures, and cancer is easily detectable.” Not so for women whose breast structure is composed less of fat and more of fibrous and glandular tissue.
Breast density is classified according to the American College of Radiology’s Breast Imaging Reporting and Data System (BI-RADS). Women are divided into type A, B, C or D, with type A having the most fat. “For women who have type A breasts, the sensitivity of mammograms is greater than 90 percent,” Jayachandran says.
On the other end of the spectrum, type D breasts have little or no fat and are predominantly made up of glands and the framework of the breast. Jayachandran says that about 40 percent of all women fall in the dense breast category, either type C or D.
Dense breast tissue appears white on a mammogram. “Trying to find a cancer in type D breasts is like trying to find a snowball in a snowstorm,” Jayachandran says.
Jameson’s breasts were classified as type D. On mammograms, they looked like cloudy white structures with barely discernible features. It took another screening technique, an ultrasound, to finally expose the cancerous lump that Jameson had felt.
A variety of technologies are available for breast cancer screenings. Many clinics use digital 2-D mammography for initial screenings. Just as with X-rays, radiation is used to expose the inner workings of the breast. The resulting image is then reviewed by a radiologist for abnormalities.
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3-D mammography (also called tomosynthesis) is a newer technology that uses radiation to provide images of the breast in thin layers or “slices” from many angles, giving more detailed images. Doctors can examine individual slices to uncover anything amiss within the layers of tissue. Jayachandran notes that with the introduction of this new screening technology, her radiology team was able to find an additional one to two cancers per 1,000 women screened.
The most recent technology is automated breast ultrasound (ABUS), also known as whole breast ultrasound, which is used as a secondary screening method for women with dense breasts. ABUS is different from mammography—a robotic arm scans the breast using sound waves and 3-D technology to capture thousands of images without radiation. Also unlike mammography, ABUS can see through most dense breast tissue. Jayachandran says that her clinic implemented the technology in April and has performed about 125 exams to date. It’s too early to assess the statistical data, she says, but so far she has caught one cancer that was missed with a 2-D digital mammogram.
“We recommend that women with dense breasts consider supplementing the mammography screening with a whole breast ultrasound screening as well,” Jayachandran says. “That will help catch the cancers that were being masked on mammography because of dense breasts.”
For Jameson, the ultrasound was able to see through her dense breast tissue and show what mammograms could not: cancer.
Mammography and whole breast ultrasound complement each other—one cannot replace the other. Though whole breast ultrasounds are proven effective in locating cancers that were masked on mammograms, mammograms can still show radiologists early possible signs of cancer, such as calcification, even in women with dense breasts.
Screening technology has improved, but awareness has yet to catch up. To date, 24 states have passed laws requiring that women be notified in their mammography report whether they have dense breasts, according to the advocacy group Are You Dense. Illinois law does not mandate that women be told whether they have dense breasts; instead it simply requires a summary of the meaning and consequences of dense breast tissue.
However, Illinois law does require that if a routine mammogram reveals dense breast tissue, insurance must cover a secondary ultrasound screening—as long as the physician deems it medically necessary.
“We always tell our patients their breast density,” says Kirti Kulkarni, MD, assistant professor of radiology at University of Chicago Medicine. “That is how we fill in the gap. We know the [mandatory notification] law will pass at some point, and we wanted to start the practice of talking about it with the patients. All of the screening patients get a letter explaining their breast density, whether they are type A or D.”
After a patient receives a letter noting her breast density, she can talk to her primary care physician about whether additional screening is necessary, Kulkarni says. Additional screening options include a whole breast ultrasound or a breast MRI, which can be used for patients with an increased lifetime risk of breast cancer or with a genetic mutation.
The best way to ensure that women have all the information they need is through education and awareness. Jameson has now devoted her life to sharing her story and spreading the word about breast density and cancer screenings, most notably through her TEDx talk and participation in the “Dangerous Boobs Tour,” an education effort by breast density awareness organization Each One Tell One.
Jameson hopes that by telling her story she can encourage other women to find out whether they have dense breasts and to ask their doctors about appropriate screenings. If you’re dense, she says, then you have to be smart.
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