Dense breast tissue is itself a risk factor for breast cancer. The thicker tissue also appears white on X-ray mammograms, the same as breast cancers, so it can be difficult to find smaller cancers masked by areas of dense tissue. Other imaging modalities like breast MRI, breast ultrasound and 3D mammography can be used in patients with dense breasts to see through the dense tissue and better identify cancers.

Having dense breast tissue is a risk factor many women are unaware that they have. Up until about a decade ago, there were no laws requiring that radiologists or healthcare organizations inform patients they are at increased risk of cancer or that they could possibly be subject to having cancers missed on their annual mammograms due to increased breast density. 

Since then, numerous states have enacted laws that require radiologists or healthcare organizations to inform patients if they have dense breast tissue. The laws in some states also call for insurance companies to cover the cost of supplemental screening exams like ultrasound and breast MRI, which can be better at detecting cancers and seeing through dense tissue. These laws now exist in about 40 states. 

This movement to create the laws was started by a patient who ended up having breast cancer, but was not diagnosed early because she had dense breast tissue and the radiologist missed the cancer on her annual screening mammograms. At that time, there was no requirement to tell her she was at increased risk of cancer or that her mammograms are difficult to read because of her breast tissue density. She lobbied state governments and radiology medical societies to bring the density issue to the forefront of discussions on mammography, patient education and to create these laws.

Lewin shared insight with Health Imaging into the impact these laws have had on women and imaging organizations.

"Do these laws increase screening? Absolutely," said Lewin. 

However, the language in the registration between the states that have adopted breast density inform laws varies.

In Connecticut, where Lewin is, he said the law allows women with dense breast tissue to get a screening ultrasound in addition to their screening mammogram, and at most they will pay $20. And as a consequence of the law, he said insurance payers are required to pay for the screening ultrasounds. As a result, he said Yale sees a large number of screening ultrasounds of women with dense breast tissue.

In Colorado, where Lewin formerly practiced, screening breast ultrasounds are also required to be covered by insurance, but the insurance companies usually include the costs in the patient's deductible. Since most younger patients are healthy, many do not not meet their deductible limits and sometimes do not want to pay extra for the ultrasound. As a result, he said the number of ultrasound screenings are lower there than in states like Connecticut, where the law is stronger and spells out what insurance companies can charge patients.

"Most of these patients are healthy, so they are essentially paying out of pocket for their screening ultrasound, and that definitely tamps down the number of screening ultrasound of these patients," Lewin said.