Having Dense Breast Tissue Calls For Different Approach to Breast Cancer Screening
With a few clicks on her computer, Amy Kerger, DO, pulls up the 2-dimensional X-ray images from a couple of mammograms.
On the first, the cancerous tumor is obvious, as the relatively large and white mass stands out against a sea of much darker breast tissue. The second mammogram is confusing, with several white spots dispersed throughout the image of the breast.
Are they breast cancer tumors?
“There’s a masking effect in women with dense breast tissue,” explains Kerger, an assistant professor and breast radiologist with the Stefanie Spielman Comprehensive Breast Center.
Dense breast tissue shows up as white on a mammogram, while fatty breast tissue is black. “And, because the tumors are white, there’s a masking effect within dense breast tissue,” she said.
The masking effect of dense breast tissue presents a diagnostic problem for radiologists. The Breast Center is a world leader in this field, and in recent years, the increased use of a 3-dimensional digital tomosynthesis machine for women with dense breast tissue has allowed Kerger and her colleagues to better unmask these hidden tumors.
Kerger pulls up an image from the tomosynthesis machine. At first glance, it looks the same as the 2-D image from a standard mammogram. And then, she clicks the mouse … and the image begins to move, rotating from the top to the bottom of the breast.
“I can see the tissues and ducts changing,” Kerger said, adding she can change the speed in which the image rotates. “We can see through the dense tissue a lot better and decrease the masking effect.”
The Breast Center is the outpatient care facility of The Ohio State University Comprehensive Cancer Center – James Cancer Hospital and Solove Research Institute (OSUCCC – James). Across all screening locations, the OSUCCC – James performs about 45,000 breast cancer screenings a year. This high number is important because clinician experience — and high-tech equipment such as the tomosynthesis machine — are vital in detecting breast cancer in its earliest stages, when it has yet to spread to other parts of the body and is easier to treat and cure.
“We’ve been doing this a long time, we’re specialists and experts,” said Kerger, who along with the other radiologists at Spielman, only looks at breast images. “And, the more often you do this, the more mammograms and tomos you look at, you’re better able to recognize the subtleties and detect tumors in dense breast tissue.”
There are four basic types of breast tissue.
About 10 percent of women have what’s called “fatty breast tissue.”
Women with “scattered fibroglandular tissue” have a lesser proportion of fatty tissue, but still more of this than the fibroglandular tissue found in the milk ducts and glands of the breast. About 40 percent of women fall into this category.
The 50 percent of women in these two categories are considered to have fatty breast tissue and abnormalities in their mammograms are easier to read.
Women with “heterogeneously dense tissue” have more fibroglandular tissue than fatty tissue. These women comprise 40 percent of the population.
Ten percent of all women have extremely dense breast tissue, which indicates a very high proportion of fibroglandular tissue.
The 50 percent of the women in these two latter categories have dense breast tissue. Under the Ohio Breast Density Law passed in 2015, they must be notified of this after a screening. The letter provided to these patients states that this “information is not provided to cause undue concern; rather, it is to raise awareness and promote discussion with your health care provider regarding the presence of dense breast tissue in addition to other risk factors.”
A discussion with a physician is the key.
“The question to ask is, ‘Do I need to do more than a 2-D mammogram?’” Kerger said. “And, to determine this, the physician should be looking at what risk factors the woman may have.” Risk factors include: family history; being overweight or drinking alcohol in excess; having had a previous breast biopsy, even if it was negative; and the previous removal of a high-risk lesion.
If a woman has a 20 percent or greater lifetime risk of developing breast cancer based on her physician’s analysis, then a yearly tomosynthesis screening is recommended. If the risk is less than 20 percent, the standard mammogram is sufficient.
However, women with dense breast cancer and a 20 percent or greater risk of developing breast cancer still need the traditional 2-D mammogram in addition to the tomosynthesis. “The 2-D mammogram spots calcifications better, and they’re an early sign of breast cancer,” Kerger said. “The tomo doesn’t see the calcifications as well.”
The tomosynthesis digitally takes multiple X-rays of each breast, in 1-millimeter slices. Some women are reluctant to utilize the tomosynthesis machine due to concerns over the increased radiation exposure during the screening.
“It’s really no different than the amount of radiation on a three-hour flight to San Francisco,” Kerger said. “And new software allows us to use the tomo and then put it into 2-D, and this reduces the radiation level back to where it was.”
Kerger cares about every one of the Breast Center’s patients.
“I’m one of the first people women meet during this process and I hope my positivity and compassion makes their journey a little easier,” she said. “I want to help women catch breast cancer early and go on to lead long and productive lives.”