SAN FRANCISCO (KCBS RADIO) — Cancer can go undetected in what doctors call "dense breast tissue," but there hasn't been any federal regulation around if, or how, mammography centers tell patients about potential risks and additional screening options. That is, until now.
A new federal law just took effect that requires mammography facilities to notify patients if they have dense breast tissue.
"So the idea is that you're informing women that they have dense breasts, which carry some risk of hiding a tumor, and it also carries some risk of increasing their risk of breast cancer," Dr. Karla Kerlikowske, professor in the departments of medicine and epidemiology and bio-statistics at UCSF School of Medicine, told KCBS Radio's Patti Reising on this week's episode of "As Prescribed."
Breast density is determined only by mammograms – having dense breasts makes it more difficult for X-rays to pass through the breast tissue and can mask tumors.
"If someone has what they call dense breasts, they have a lot of the fibroglandular, collagen, connective tissue -- they can have the same isodensity as a breast tumor. So it can hide the breast cancer, but also all that cellular content increases the risk of breast cancer," said Dr. Kerlikowske. "If you have more fatty and less glandular tissue, your risk of breast cancer and of not being able to see a tumor is less."
Under the new law, mammography facilities must provide all patients receiving a mammogram with one of two federal breast density notification statements -- either "not dense" or "dense." If you receive the "dense" designation, Dr. Kerlikowske said the most important thing is to not worry.
"Density alone does not mean that you're necessarily at increased risk of breast cancer. It's really the combination with other risk factors that increases your risk," she said. "I mean, you know, 47% of women have dense breasts, right? And 47% of women do not get breast cancer, and 47% of women do not get their tumor missed on mammograms."
"It's probably most important just to discuss it with your provider," she added.
Patients with dense breasts may be referred for supplemental imaging tests, such as a tomosynthesis or 3D mammogram. However, there's still debate around the medical significance of dense breasts and whether extra screening should be done.
"I think it's because [radiologists] do feel that the standard mammograms are quite good, and that the chance of missing a cancer, even in people who have dense breasts, is quite low," said Dr. Kerlikowske.
"Many of the studies that have done supplemental imaging, whether it's screening ultrasound or screening MRI, they find more tumors. And the question is, are they just finding them earlier? They would find them later on mammography anyway. And does it really have an impact on decreasing the worst tumors or breast cancer mortality? And that has not been answered," she added.
Listen to this week's "As Prescribed" to learn more. You can also listen to last week's episode to hear why young athletes should diversify their sports, here.
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“As Prescribed” is sponsored by UCSF.