Fast Breast MRI Seems to Find More Cancers in Dense Breasts Than 3D
Written by: Jamie DePolo, senior editor
A 10-minute breast MRI exam called Fast Breast MRI found more cancers than 3D mammograms in women with dense breasts, according to a study.
The research was published on Feb. 25, 2020, by the journal JAMA. Read the abstract of “Comparison of Abbreviated Breast MRI vs Digital Breast Tomosynthesis for Breast Cancer Detection Among Women With Dense Breasts Undergoing Screening.”
What is Fast Breast MRI?
Traditional breast MRI uses magnets and radio waves to produce detailed 3D images of breast tissue after a contrast dye is injected into a vein. Breast MRI is not limited by breast density, and research has shown that it is more sensitive than mammography at finding breast cancer. Still, breast MRI is not perfect. Research has shown that breast MRI results in more false positives than mammography. A false positive is when a test finds something that initially looks suspicious but turns out not to be cancer.
Traditional breast MRI is also more expensive than a mammogram and takes longer to perform — 45 minutes compared to about 15 minutes for a mammogram. Breast MRI also requires the contrast dye injection, which some people find uncomfortable. The dye also may affect the kidneys, so your doctor may perform kidney function tests before the dye is injected.
So, traditional breast MRI is not recommended as a screening tool for all women — only for women at high risk of breast cancer.
Fast Breast MRI still requires the contrast dye injection but takes only 10 minutes to perform, rather than 45 minutes. Because Fast Breast MRI takes less time than traditional breast MRI, the cost and complexity of the test are also lower.
Right now, Fast Breast MRI is not covered by insurance, so women must pay out of pocket for the exam. The average cost is $250.
What is 3D mammography?
Three-dimensional (3D) mammography (also called digital breast tomosynthesis, digital tomosynthesis, or just tomosynthesis) creates a 3D picture of the breast using X-rays. Several images from different angles around the breast are used to create the 3D picture.
A conventional mammogram creates a two-dimensional image of the breast from two X-ray images of each breast.
3D mammography is approved by the U.S. Food and Drug Administration (FDA) and is a standard of care for breast cancer screening. Because it’s a newer technology, it may not be available at all hospitals and mammogram facilities.
What is breast density and how is it measured?
Dense breasts have less fatty tissue and more non-fatty tissue compared to breasts that aren't dense.
One way to measure breast density is the thickness of tissue on a mammogram. The BI-RADS (Breast Imaging Reporting and Database System), which reports the findings of mammograms, also includes information on breast density. BI-RADS classifies breast density into one of four groups:
- mostly fatty
- scattered areas of density
- consistently dense
- extremely dense
Still, no one method of measuring breast density has been agreed upon by doctors. Breast density is not based on how your breasts feel during your self-exam or your doctor's physical exam. Dense breasts have more gland tissue that makes and drains milk, and more supportive tissue (also called stroma) that surrounds the gland. Breast density can be inherited, so if your mother has dense breasts, it's likely you will, too.
Research has shown that dense breasts can:
- be twice as likely to develop cancer as non-dense breasts
- make it harder for mammograms to detect breast cancer because breast cancers (which look white like breast gland tissue) are easier to see on a mammogram when they're surrounded by fatty tissue (which looks dark)
Nearly half of women age 40 and older in the United States are classified as having dense breasts.
Because mammograms can have a hard time finding breast cancer in dense breasts, researchers have been looking for other cost-effective ways to screen dense breasts for cancer.
How this study was done
The study included 1,444 women age 40 to 75 with an average risk of breast cancer and dense breasts, based on their most recent mammogram.
- 77% had consistently dense breasts
- 15% had extremely dense breasts
The study was done between December 2016 and November 2017 at 47 sites in the United States and one site in Germany.
In a 24-hour period, the women were randomly assigned to have either:
- Fast Breast MRI followed by a 3D mammogram
- a 3D mammogram followed by Fast Breast MRI
The images were read independently by two different board-certified radiologists who did not know the results of the other screening test.
Overall, 17 women were diagnosed with invasive breast cancer and six women were diagnosed with non-invasive breast cancer (DCIS).
Fast Breast MRI found all 17 invasive cancers and five out of six DCIS lesions.
3D mammography found 7 of 17 invasive cancers and two out of six DCIS lesions.
The invasive cancer detection rate was:
- 11.8 per 1,000 women for Fast Breast MRI
- 4.8 per 1,000 women for 3D mammography
This difference was statistically significant, which means that it was likely due to the difference in screening methods and not just because of chance.
For detecting invasive breast cancer, sensitivity (the ability to correctly identify those with the disease) was:
- 95.7% for Fast Breast MRI
- 39.1% for 3D mammography
Additional imaging was recommended at a rate of:
- 7.5% for Fast Breast MRI
- 10.1% for 3D mammography
“When screening women at average risk with dense breasts, we found that [Fast Breast MRI] detected significantly more — almost two and a half times as many — breast cancers as 3D mammography,” said Christopher Comstock, M.D., of Memorial Sloan Kettering Cancer Centers and lead author of the study. “We also found that [Fast Breast MRI] was well tolerated by women, with very few side effects.”
“While these early results are promising, further studies are needed to evaluate the cost-effectiveness of widespread screening with [Fast Breast MRI] and its impact on reducing breast cancer mortality,” he continued. “Currently, only a few centers offer [Fast Breast MRI] and it is not covered by insurance. Our hope is that [this] study…will provide the impetus for more centers to provide this new test and that insurers will see its benefit to improve early detection of breast cancer.”
What this means for you
While the results of this study are encouraging for women with dense breasts, they are early results. More research is needed before we know:
- if finding these breast cancers earlier leads to better survival for women
- how these breast cancers would affect a woman’s health and life if they were never found
If you have dense breasts, you and your doctor will develop a screening plan tailored to your unique situation. General recommended screening guidelines include:
- a monthly breast self-exam
- a yearly breast exam by your doctor
- a digital mammogram every year starting at age 40
Your personal screening plan also may include:
- breast MRI
- breast ultrasound
Talk to your doctor about developing a specialized program for early detection that meets your individual needs and gives you peace of mind.
To get the best information from your breast imaging studies, it's important to:
- compare this year's study to prior years' studies
- correlate the information from the imaging studies (what you feel in the breast compared to the results of your mammogram, MRI, and ultrasound)
For more information on mammograms, ultrasound, and other tests used to detect breast cancer, visit the Breastcancer.org Screening and Testing pages.
Written by: Jamie DePolo, senior editor