Mammograms and ultrasound imaging have to scan through layers of tissue to find budding breast cancers. But scans with MRI -- magnetic resonance imaging -- provide detailed, cross-sectional images of the inside of the breast. It finds more suspicious areas than other techniques.
The problem with MRI is that it is too good. That is, it finds a lot of suspicious spots that turn out not to be breast cancer. For most women, routine MRI screening would mean many unnecessary biopsies and a lot of unnecessary anxiety.
It's a different story for women whose family histories or genetic inheritance put them at very high risk of breast cancer. Suspicious MRI findings in such women all too often turn out to be cancer. And early detection is the key to cure.
That's why the ACS convened an expert panel to determine exactly which women should -- and should not -- get regular MRI breast cancer screening. Panel chair Christy Russell, MD, is co-director of the University of Southern California breast center.
"These guidelines are a critical step to help define who should be screened using MRI in addition to mammography," Russell says in a news release. "Women at very high risk of breast cancer can be diagnosed much earlier when combining the two technologies rather than using mammography alone."
Which Women Need Breast MRI?
The ACS panel says women should get annual breast MRIs if:
- They carry mutations in the BRCA1 or BRCA2 breast cancer genes.
- They have a parent, sibling, or child with a BRCA1 or BRCA2 mutation, even if they have yet to be tested themselves.
- Their lifetime risk of breast cancer has been scored at 20%-25% or greater, based on one of several accepted risk-assessment tools that look at family history and other factors.
- They had radiation to the chest between the ages of 10 and 30.
- They have a rare medical condition linked to breast cancer -- Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome -- or have a parent, sibling, or child with one of these syndromes.
"The actual number of women seeking MRI screening in addition to mammography is expected to be much lower than 1 in 50 -- at least for the foreseeable future," say Debbie Saslow, PhD, ACS director of breast and gynecologic cancer, and Robert Smith, PhD, ACS director of cancer screening, in a statement released to WebMD.
Other women may benefit from MRI screening, but there's not yet enough evidence to include them in the screening recommendation. The ACS says "the jury is still out" on whether the benefits of MRI screening outweigh the risks for women with:
- A 15%-20% lifetime risk of breast cancer, based on one of several accepted risk-assessment tools that look at family history and other factors
- Lobular carcinoma in situ (LCIS) or atypical lobular hyperplasia (ALH)
- Atypical ductal hyperplasia (ADH)
- Very dense breasts or unevenly dense breasts (when viewed on a mammogram)
- Previously diagnosed breast cancer, including ductal carcinoma in situ (DCIS)
The new recommendation comes with a warning: Not all doctors' offices have the proper MRI equipment. Women should not get MRI screening at a practice that does not also offer MRI-guided biopsies, the ACS warns.
MRI Helps Women With New Breast Cancer
Separately, a new study complements the ACS recommendations. It shows that for women with a new diagnosis of cancer in one breast, MRI is much better than mammography for determining whether the other breast carries a cancer. Constance Lehman, MD, PhD, director of breast imaging at the University of Washington and Seattle Cancer Care Alliance, was one of the study’s researchers.
"This means that instead of those women having another cancer diagnosis years after their initial treatment, we can diagnose and treat those opposite-breast cancers at the time of the initial diagnosis," Lehman says in a news release.
Perhaps more importantly, MRI can all but rule out cancer in the second breast.
"Although no imaging tool is perfect, if the MRI is negative, the chance of cancer in that breast is extremely low," Lehman notes. "A potential outcome that we would be delighted to see is fewer unnecessary bilateral mastectomies."
Lehman and colleagues report their findings in the March 29 issue of The New England Journal of Medicine.