In real-world practice, breast MRI is being overused in women who won’t benefit and might even be harmed by it, but at the same time underused by the women who could gain the most from it, according to two separate studies reported online Nov. 18 in JAMA Internal Medicine.
The two large cohort studies, which involved different patient populations and different methodologies, had remarkably similar findings. In addition to the widespread overuse and underuse of breast MRI, both studies found that overall use of the technology has soared since the year 2000 for a variety of indications, even though the evidence only supports its use for a few particular indications.
Thankfully, that rapid increase appears to have plateaued in the most recent years for which data are available, both research groups noted.
Both studies were performed simply to gather data on national patterns of breast MRI use in community practice, because of the dearth of information on this topic.
National guidelines support breast MRI to screen asymptomatic women only if they are at high risk for breast cancer because they carry BRCA gene mutations, are first-degree relatives of BRCA carriers but haven’t been tested themselves, or are at more than 20% lifetime risk of breast cancer according to risk assessment tools based on family history.
In the first study, investigators assessed breast MRI use using data from five regional registries participating in the Breast Cancer Surveillance Consortium. The study population comprised women aged 18-79 years who had breast MRI (8,931 exams in 6,777 subjects) and/or screening mammography (1,288,924 subjects) during 2005-2009, reported Karen J. Wernli, Ph.D., of Group Health Research Institute, Seattle, and her associates.
During the relatively brief study period, the overall use of breast MRI nearly tripled, from 4.2 to 11.5 exams per 1,000 women. The total number of exams rose steeply during the first 2 years, from 863 in 2005 to 2,264 in 2007; it then remained stable at about 2,150 per year through 2009.
Overall, only 25% of women who had screening breast MRI were considered at high lifetime risk for breast cancer and thus fit the recommended criteria for the procedure. That proportion was only 9% in 2005, and it rose to 29% in 2009.
It appears that most of these women and their clinicians overestimated their breast cancer risk. They may obtain more accurate assessments by using approved risk calculators rather than by relying on family history alone, Dr. Wernli and her colleagues said (JAMA Intern. Med. 2013 Nov. 18 [doi: 10.1001/jamainternmed.2013.11963]).
Conversely, fewer than 5% of the approximately 25,200 study participants deemed to be at high lifetime risk for breast cancer underwent screening breast MRI. Previous studies have reported that the most common reasons that high-risk women cite for forgoing breast MRI were claustrophobia, time constraints, financial concerns, a physician who didn’t endorse the procedure, lack of patient interest, and lack of access to the technology.
In the second study, investigators assessed the use of breast MRI from 2000 through 2011 in a large, not-for-profit health plan covering more than 1 million patients throughout New England. The study population involved 10,518 women aged 20-89 years (mean age, 49 years) who had 18,215 breast MRI exams, reported Natasha K. Stout, Ph.D., of the department of population medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, and her associates.
Overall use of the procedure increased 14-fold during the study period, from 198 per 10,000 women in 2000 to 2,744 per 10,000 in 2011. As in the previous study, there was a steep rise in breast MRI use until approximately 2008, followed by a leveling off. This coincides with the release of American Cancer Society guidelines in 2007 recommending breast MRI as a screening tool only for women at high risk of breast cancer, Dr. Stout and her colleagues said.
Only 21% of the women who underwent screening breast MRI were at high risk and thus met the recommended criteria for the procedure. And fewer than half of the women who were at high risk by virtue of their BRCA status or family history underwent breast MRI (JAMA Intern. Med. 2013 Nov. 18 [doi: 10.1001/jamainternmed.2013.11958]).
"Understanding who is receiving breast MRI and the downstream consequences of this use should be a high research priority, to ensure that the limited health care funds available are used wisely to maximize population health," Dr. Stout and her colleagues said.
Dr. Wernli’s study was supported in part by the National Cancer Institute and the Agency for Healthcare Research and Quality. Dr. Wernli reported no financial conflicts of interest; her associates reported ties to GE Medical Systems, Phillips Medical Systems, and other companies. Dr. Stout’s study was supported in part by the American Cancer Society and the National Center for Research Resources. Dr. Stout and her associates reported no financial conflicts of interest.