Shedding Light on Breast Density
Radiologists discuss the implications of breast density legislation.
Politics and health care are not unusual bedfellows. Health care is something we all need, which means everyone — including government task forces and state legislators — has ideas about what's best for themselves as well as others, and some have the power to turn recommendations into mandates or legislation.
Not surprisingly, some recommendations can occasionally miss the mark, like the United States Preventive Services Task Force guidelines in 2009, which stated routine screening mammograms were unnecessary for women younger than 50. The guidelines caused a fervent backlash in the radiology community, which asserts the benefits of mammograms beginning at age 40.
Now the legislative issue surrounds the topic of breast density. Should patients be notified if they have dense breasts? How can radiologists and physicians help patients understand the relevance of breast density? Should physicians recommend such patients seek additional imaging? Connecticut was the first state to pass a law, in 2009, related to breast density notification, which requires that physicians send letters to patients informing them of their breast density based on the mammograms. Texas, Virginia, New York, and Utah (see sidebar, "In One Radiologist's Words") have since followed with similar legislation.
Importance of Density
As all breast imagers know, dense breasts make mammograms more difficult to interpret. But as for what role density plays in the risk of breast cancer, the verdict is still unclear. "If a patient's breasts are considered nondense, and she goes on a diet and loses 100 pounds, her breasts may appear denser. Does that increase the risk for breast cancer?" asks Carl J. D'Orsi, MD, FACR, emeritus director of Emory University's Division of Breast Imaging in Atlanta. "That's the question you have to ask. Density does play some part."
Density as an aspect of risk is also uncertain in journal literature. "Density is overstated as a risk factor in some sources and papers, so it's not clear to everyone how density fits into an overall risk assessment," says Debra L. Monticciolo, FACR, MD, president of the Society of Breast Imaging.
To formally make this point, the College developed a position statement on the issue in April, which notes that the College has always supported the inclusion of breast parenchymal density information in the mammography report. However, "While the ACR is not opposed to including breast parenchymal information in the lay summary [to patients], we urge strong consideration of the benefits, possible harms, and unintended consequences of doing so," the statement reads. "For women with dense breasts, receipt of breast density information may create undue anxiety about their risk."
Drawbacks of Legislation
And although patients may be able to calm their anxiety with access to more health information than ever before, many radiologists are concerned that including density in the lay summary could confuse patients. The Connecticut legislation, for example, states that the "[lay summary], where applicable, shall include the following notice: 'If your mammogram demonstrates that you have dense breast tissue, which could hide small abnormalities, you might benefit from supplementary screening tests, which can include a breast ultrasound screening or a breast MRI examination, or both, depending on your individual risk factors.'"
Breast density "is not all of the information a woman needs to make a decision whether she needs supplemental screening," says Barbara S. Monsees, MD, FACR, chair of the ACR Commission on Breast Imaging, and the Ronald and Hanna Evens Professor of Women's Health at Washington University School of Medicine in St. Louis. "The important thing is that density information should be available to the patient when discussing with her physician what imaging is right for her." The ACR recently developed a brochure to help patients understand the implications of dense breasts (see sidebar, "Brochure Helps Patients Understand").
Another substantial issue is the lack of standardization of breast density evaluations. "Right now, breast density assessment is not standardized. It's a subjective visual assessment," says Laurie L. Fajardo, MD, MBA, FACR, professor of radiology at the University of Iowa Division of Breast Imaging in Iowa City, Iowa. "I've seen radiologists give a patient's density a BI-RADS® rating of scattered fibroglandular densities one year, and the next year they rate it as heterogeneously dense breast tissue. Or you often get two radiologists who give two different ratings to the same mammogram."
Additionally, unless states require payers to cover supplemental screening options, many patients will go without. "Advocacy to ensure women with dense breasts receive more detailed imaging that mammography alone is well-placed, but many supplemental examinations are not reimbursed," says Fajardo. "Women who are underinsured or who can't afford them may not get those options."
What to Do
"This is not the same as bone density imaging," notes Fajardo. "With that, you have the opportunity to alter your density by changing your diet or through medication. I think there's a kind of misconception that there's something women can do to change their breast density."
Regardless, bone densitometry had a similar problem in its infancy related to standardization. "A patient would have a bone scan one year on one machine and the next year on another. The results were not correlative," says Fajardo. Not correlative, that is, until machines and software were developed to gauge bone density more accurately and uniformly.
"Some companies have been working on quantifying area and volume measurements for breast density, but these measurements would have to be validated to be consistent and to predict risk. In addition, we can't require that radiologists use specific vendors," says Monsees.
But innovations in technology may also lead to more questions. "Professional societies need to agree on the standard and on how we report BI-RADS categories, or they need to decide on a more quantitative solution," says Fajardo. "Many software programs are attempting to look at digital mammograms and come up with ways to quantify pixel value and tissue heterogeneity, but they're all different. Which program should we use? How would we report it to women? This could potentially be very confusing to women."
D'Orsi mentions a 2008 article in Radiology in which Daniel B. Kopans, MD, FACR, writes, "Computerized segmentation algorithms can accurately assess the percentage of the X-ray image that is 'dense,' but this does not accurately measure the true volume of tissue ... Future investigations need to use three-dimensional information."1 Indeed, D'Orsi suggests that the only way to obtain the actual volume of density is via isotropic 3-D exams. "2-D exams (routine mammography)," he says, "and even tomosynthesis will not produce reliable, true volumetric evaluations."
What About Screening Ultrasound?
The benefits and risks of supplemental screening may also be confusing. Although Monticciolo notes that "the most sensitive option for detecting breast cancer in breast MRI, screening ultrasound is another possibility, though it generates a lot of false-positives."
Beyond false positives, many radiologists believe that implementing screening ultrasound is simply not viable given the manpower it requires. Regina J. Hooley, MD, assistant professor of diagnostic radiology at the Yale School of Medicine in New Haven, Conn., and her colleagues disagree: "Our key finding was that you can incorporate screening ultrasound in a busy breast imaging practice." After completing a study published online in June ahead of print in Radiology, Hooley concluded, "Although a lot of radiologists may not think it's feasible because it's physician time-intensive and operator-dependent, I think it is feasible."2
After the Connecticut legislation passed in 2009, Hooley knew immediately that she wanted to gather data related to screening ultrasound. She imagined a use of this supplemental screening modality, along with mammography, would increase and would generate a new chapter in research for the entire breast imaging community. It was also something her practice at Yale didn't yet offer.
Hooley's practice was able to provide screening ultrasound because of additional laws passed in 2005 that require insurers to cover screening breast ultrasound if requested by the patient's physician. "The purpose of the study was to determine the utilization and performance of screening breast ultrasound in women who presented to our breast imaging practice with dense breast tissue in the first year since the implementation of [the Connecticut] law," Hooley told AuntMinnie.com.
"Yes, we had a lot of false-positive results and frequent need for follow-up for BI-RADS in 3 cases, but we also identified a lot of complicated cysts," notes Hooley, whose group used handheld ultrasound performed by technologists. "And after we designed some criteria to guide us in the management of these cases, our BI-RADS 3 cases decreased without a loss of sensitivity. We're finding small, mammographically occult cancers at a significant rate, and we're able to do that and still be efficient."
But for others, the false-positives of screening breast ultrasound can outweigh the positives. "At a certain point, you pay such a high price in false-positives to get a very small reward in increased cancer detection," says D'Orsi. "So the ideal imaging tool outside of mammography needs to be something that takes a lot into account — anxiety, cost, access, and the individuals performing the image interpretations. Those are things that the Connecticut legislation never took into account."
Like other major concerns in radiology, many sides and representative groups — patients, physicians, radiologists, legislators, technology developers, researchers, and so on — went to weigh in. Some radiologists, like Hooley, moved ahead with imaging options they're able to provide to patients, while others feel more information is needed.
This additional information might have been especially useful for legislators before the Connecticut legislation was passed. "It's a big mistake to legislate this kind of issue — the data isn't there," says D'Orsi. "Even with the very food intentions of the legislators, once it's a law, that's it. Before I'd put anything into a law, I'd make sure it was bulletproof."
1. Kopans D. "Basic Physics and Doubts about Relationship between Mammographically Determined Tissue Density and Breast Cancer Risk." Radiology. February 2008;246;348-353.
2. Hooley RJ, Greenberg KL, Stackhouse RM, et al. "Screening US in Patients with Mammographically Dense Breasts: Initial Experience with Connecticut Public Act 09-41." Radiology. Published online June 21, 2012.
By Raina Keefer