CHICAGO — This month, a new Food and Drug Administration (FDA) regulation goes into effect requiring all mammography facilities in the U.S. to notify women of their level of breast density. Although many centers have already been doing this for several years, the FDA regulation expands the requirement to all breast centers across the country.
With the new regulation, many women may have questions about what exactly breast density is and how it impacts their risk of developing breast cancer. The American College of Surgeons National Accreditation Program for Breast Centers (NAPBC) standards, revised last year to emphasize individualized patient care, also require accredited centers to notify and educate patients on breast density, emphasizing the opportunity for collaboration between radiologists and surgeons. Radiologists on the NAPBC board offered insight into what women should know about breast density and why it matters.
1. Breast density refers to the ratio of fatty and fibrous tissue in the breast and is one risk factor for developing breast cancer.
The breast comprises a variety of tissue types. Breast density refers to the amount of fibrous and glandular tissue a woman has in her breasts compared to fatty tissue. Breast density, which is unique to each woman, is important for several reasons. First, having dense breast tissue may mask small masses in the breast on a mammogram. On a mammogram, fatty tissue tends to appear as dark areas, whereas dense breast tissue and cancerous changes often appear as white areas, making it harder for radiologists to distinguish between suspicious lesions or benign changes in the tissue.
“Another way to think about breast density on a mammogram is like looking at a cloudy sky and trying to differentiate things that are coming through in the sky. You’re not going to see things as well when the sky is cloudy versus when it’s clear,” said Georgia Spear, MD, division chief of breast imaging at Endeavor Health/NorthShore University HealthSystem and an NAPBC board member representing the American College of Radiology Imaging Network. “Density has the effect of masking potentially small masses that might be developing in the tissue that we can’t see well on mammography.”
In addition to masking potentially cancerous changes on mammograms, for reasons still being researched, breast density is a known risk factor for breast cancer, raising a woman’s risk of developing breast cancer by four to six-fold. Dr. Spear notes that this increased risk may be because breast cancer arises more commonly in fibrous and glandular tissue, which is more abundant in women with dense breast tissue, than in fatty tissue.
The FDA regulation, Dr. Spear added, is important because it helps women better understand their personalized risk factors for breast cancer and lets them know that they may benefit from additional screening with ultrasound or MRI.
2. Breast density can only be diagnosed through imaging.
Breast density can only be diagnosed through imaging; it cannot be seen or felt during a physical exam. According to the National Cancer Institute (NCI), four categories of breast density may be noted on a woman’s imaging report: (1) entirely fatty breast tissue, (2) scattered fibroglandular breast tissue, (3) heterogeneously dense breast tissue, and (4) extremely dense breast tissue. Women with increased breast density will fall into either the heterogeneously dense or extremely dense tissue categories.
3. Women with increased breast density may benefit from additional screening techniques.
Women with increased breast density may be recommended to receive supplemental screening with ultrasound or breast MRI. These additional screening techniques can help radiologists detect cancerous changes that may be masked by dense breast tissue seen on a mammogram and offer a woman an additional line of protection.
“Density is just one factor that we look at when we decide what’s the best way to screen a patient,” said Lora D. Barke, DO, FACR, chief of breast imaging at Invision Sally Jobe in Denver, Colorado, and an NAPBC board member representing the American College of Radiology on Breast Imaging Commission. “When we look at density, it helps us decide on some other tools that would be beneficial for that patient along with mammography. Knowing breast density provides patients with a bigger picture to make more informed decisions.”
While mammograms remain the gold standard of breast cancer screening and are excellent at spotting microscopic changes in the breast called calcifications that are not detectable on a physical exam, Dr. Barke noted that MRI and/or ultrasound may be superior in detecting small masses or other subtle changes that may be more difficult to see on a mammogram with or without digital breast tomosynthesis (3D mammography), especially in women with dense breast tissue.
Unfortunately, insurance coverage for supplemental screening is highly variable, so imaging with MRI and ultrasound may not be fully covered for some women. The ACS supports the Find It Early Act, which would require health insurance plans to cover screening and diagnostic breast imaging, including mammograms, breast ultrasounds, and MRIs with no cost sharing for patients. The bill currently has 59 bipartisan cosponsors in the House of Representatives.
4. A woman’s breast density level may change over time.
Women should not panic if they receive notice of having dense breast tissue, as it is extremely common. In fact, nearly half of women 40 and older have dense breast tissue, according to the NCI. In particular, younger women are prone to having more dense breast tissue. While density may sometimes remain constant, the tissue can also become less dense over time, especially as women age and if they have children.
“We record the category of breast density every single time a patient visits us, so it’s something that we monitor from year to year on a mammogram,” said Jocelyn Rapelyea, MD, associate director of breast imaging at GW Medical Faculty Associates in Washington, D.C. “If you are informed that you have dense breast tissue on your mammogram report, my advice is to discuss that finding with the radiologist as to what it means for you and what additional screening may be right for you.”
Learn more about NAPBC standards and how they are driving quality breast cancer care.
