Further Improvement Needed in Breast MRI Use in Community Practice
In a study reported in JAMA Internal Medicine, Wernli et al evaluated use of breast magnetic resonance imaging (MRI) in the community setting from 2005 to 2009. They found that although recommended use of MRI for screening of high-risk women is increasing, considerable progress is needed in ensuring appropriate use.
Study Details
This observational cohort study involved data on breast MRI and mammography use in women aged 18 to 79 years from 2005 to 2009 in five national Breast Cancer Surveillance Consortium registries. The rate of breast MRIs per 1,000 women with breast imaging within the same year was calculated, and the clinical indications for breast MRI were assessed by year and age.
Subject characteristics and lifetime breast cancer risk were compared for women screened with breast MRI vs those screened with mammography alone. Risk was assessed using the National Cancer Institute Breast Cancer Risk Assessment Tool (BCRAT).
Changes in Use and Indications
A total of 8,931 breast MRI examinations and 1,288,924 screening mammograms were included in the analysis. The rate of MRI use increased from 4.2 examinations per 1,000 women in 2005 to 11.5/1,000 in 2009, with the steepest increase occurring between 2005 and 2007. The rate of screening MRI increased from 0.8/1,000 in 2005 to 3.4/1,000 in 2007 and then remained stable at 4.3/1,000 by 2009.
Overall, the most common indications for MRI were diagnostic workup of a non-MRI or clinical finding (40%), screening (32%), cancer staging and treatment (16%), and other (12%). In 2005, 2007, and 2009, the proportions of MRIs were: 53%, 41%, and 35% for a diagnostic indication; 18%, 33%, and 34.5% for screening; 15% 16%, and 18% for breast cancer staging and treatment; and 14%, 10%, and 13% for other. Overall, screening accounted for 34% of MRIs in women aged < 40 years and 18% in women aged 70 to 79 years. Proportions of women receiving MRI for other indications were similar across age groups.
Among women screened with MRI (n = 2,831 examinations) and women screened with mammography alone (n = 1,288,924 examinations), those screened with MRI were significantly more likely to be younger (< 50 years), white (85% vs 75%), and nulliparous (33% vs 26%) and to have a personal history of breast cancer (45% vs 5%), first-degree family history of breast cancer (52% vs 17%), prior breast biopsy (not benign; 68% vs 24%), and extremely dense breast tissue (22% vs 10%) (all P < .001).
Analysis restricted to women without a history of breast cancer (1,559 MRI evaluations; 1,228,812 mammography only evaluations) showed similar significant differences; the proportion receiving MRI who had a family history of breast cancer was greater (70%), and the proportion who had prior breast biopsy was lower (35%) compared with the total population receiving MRI.
Increase in Appropriate Risk-Based Use
Overall, 25% of women receiving screening MRI had a > 20% lifetime risk of developing breast cancer and 53% had a lifetime risk of < 15% on BCRAT, compared with 2% and 92% of women receiving mammography alone. Between 2005 and 2009, the proportion of women receiving MRI who had a > 20% lifetime risk increased from 9% to 29% and the proportion with lifetime risk < 15% decreased from 74% to 50%. The proportion of women receiving mammography alone with lifetime risk > 20% was 2% in every year from 2005 to 2009; in total, 25,237 women with lifetime risk > 20% were screened with mammography alone.
The investigators concluded, “Use of breast MRI for screening in high-risk women is increasing…. We also identified a need for more appropriate risk-based use of breast MRI as a screening examination because we identified women at average risk receiving MRI screening and women at high risk not receiving MRI screening. Our findings suggest that there is a need for improvement in the use of diagnostic and screening breast MRI for women most likely to benefit from this imaging tool.”
Karen J. Wenli, PhD, of Group Health Research Institute, is corresponding author of the article in JAMA Internal Medicine.
The study was supported by grants from the National Cancer Institute–funded Breast Cancer Surveillance Consortium, National Cancer Institute, and Agency for Healthcare Research and Quality. For full disclosures of the study authors, visit archinte.jamanetwork.com.
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