Nearly half of all United States women over the age of 40 have dense breasts. Breast density is the amount of fibroglandular tissue compared to fat within the breasts of each woman and is measured on mammography. Women with dense breasts have an increased risk of developing breast cancer. Dense breast tissue also makes it more difficult for a doctor to find a breast cancer on a mammogram.

A recent study published in The New England Journal of Medicine found that magnetic resonance imaging (MRI) scans are more effective at finding breast tumors in women with dense breasts than mammography alone. The study, which included more than 40,000 women from the Netherlands with extremely dense breasts, found those who had MRIs in between mammograms had more tumors detected than those who had only mammography.

Cancer detected in between regular screening mammograms is referred to as interval cancer. Interval cancers have worse patient outcomes than cancers detected by screening. The study found that the interval cancer rate was 2.5 per 1,000 screenings in the group receiving MRIs and 5 per 1,000 in the mammography-only group. In other words, screening breast MRI cuts the interval cancers in half.

“To increase the chance of detecting breast cancers early, screening breast MRI is currently recommended for women at high risk of developing breast cancer during their lifetimes,” said Dr. Bethany Niell, Moffitt Cancer Center’s division chief of breast imaging. “Women with dense breasts and other breast cancer risk factors may qualify for annual breast MRI.”

In March, the U.S. Food and Drug Administration  proposed policy changes requiring health care facilities to notify women about their breast density and the related risks. Under current guidelines, supplemental screening is not routinely recommended based solely upon breast density.

According to Niell, The American College of Radiology is currently drafting a guideline to help women and their referring providers identify the most appropriate breast cancer screening tests for each woman based upon her breast density.

“At Moffitt, we encourage women to talk to their doctor about what screening tests may be best for them, based upon breast density and other individual risk factors. We also recommend that every woman over the age of 40 receive a screening mammogram each year,” Niell said. She adds that 30% to 40% of women are not receiving regular mammograms, and an even higher percentage of high-risk women do not undergo regular screening breast MRI.

If you haven’t had a recent screening mammogram or need to talk to a doctor about your risk factors for breast cancer and which tests in addition to mammography might be right for you, contact us today to set up an appointment.

Moffitt offers high risk clinic appointments, mammograms, ultrasound examinations, and breast MRI at our McKinley and International Plaza locations.

UPDATE: A previous version of this story showed an image of a patient face up in the MRI tunnel. The correct position for this procedure is face-down with feet first into the scanner.