Preoperative breast MRI associated with more testing and mastectomies

Preoperative magnetic resonance imaging (pMRI) for breast cancer increased eight-fold over a 10-year period among women newly diagnosed with breast cancer in Ontario, Canada.

Also, use of pMRI was associated with higher likelihood of postdiagnosis breast imaging and biopsies, staging imaging, mastectomy, contralateral prophylactic mastectomy, and a greater than 30-day wait to surgery, according to a study published online September 24, 2015 in JAMA Oncology.

Current guidelines recommend bilateral mammography as the primary imaging modality and, if necessary, preoperative ultrasonography. But use of pMRI has grown in recent years due to its potential to detect occult disease not seen with traditional breast imaging.

“However, compared with mammography, breast MRI has a modest specificity that leads to higher false-positive rates, is more expensive, and requires the use of intravenous contrast medium,” the authors wrote.

In addition, previous studies have consistently shown that pMRI fails to improve surgical outcomes, breast cancer recurrence rates, or survival.

In this population-based retrospective cohort study, Angel Arnaout, MD, MSc, of The Ottawa Hospital and the University of Ottawa, Ontario, Canada, and coauthors used administrative health care databases throughout Ontario to include 53,015 women with newly diagnosed primary operable breast cancer treated from 2003 to 2012.

The authors found that 14.8% of women (7,824) had preoperative MRI, and most of these patients (65%) underwent breast-conserving surgery. Also, use of preoperative MRI increased eight-fold across all stages—from 3% of newly diagnosed patients in 2003 to 24% in 2012.

After analyzing the data, the researchers determined that preoperative breast MRI was associated with a higher likelihood of:

• Post-diagnosis breast imaging (odds ratio [OR] 2.09)
• Post-diagnosis breast biopsies (OR 1.74)
• Post-diagnosis imaging for distant metastatic disease (OR 1.51)
• Mastectomy (OR 1.73)
• Contralateral prophylactic mastectomy (OR 1.48)
• Greater than 30-day wait to surgery (OR 2.52)

Patient factors associated with MRI use were younger age, higher socioeconomic status, and higher comorbidity score. Clinical factors included surgery performed in a teaching hospital, and fewer years of surgeon experience.

Other influences that may have contributed to the growth in pMRI use include the increased availability of MRI scanners, rising patient demand, institutional pressure to use expensive capital equipment, and potential radiologists’ self-referral for diagnostic imaging services, the authors speculated.

“Irrespective of the reasons for increased pMRI use, in an era of ever-increasing focus on cost containment in health care, consideration must also be given to the unintended consequences of those who undergo pMRI. The increased sensitivity of breast MRI is achieved at the cost of lower specificity,” the authors wrote. “In practice, this translates into more confirmatory imaging and biopsies needed to rule out a diagnosis of cancer.”

“This study adds to the growing body of evidence that the use of MRI in the preoperative setting is associated with more aggressive surgery of the affected breast,” wrote Habib Rahbar, MD, of the University of Washington, in Seattle, WA, and Constance D. Lehman, MD, PhD, of Massachusetts General Hospital, in Boston, in an accompanying editorial. “It may be that advanced imaging, such as MRI, is unlikely to lead to better outcomes in the context of treatment paradigms developed in settings of conventional imaging.”

But, they added, “Because MRI can detect occult disease with high sensitivity, future research might explore its role in novel treatment approaches, such as whether it can identify patients for whom multiple lumpectomies for multicentric disease (in lieu of mastectomy) or for whom lumpectomy without radiation for unifocal low-risk disease are appropriate. It is this role in precision diagnostics and risk-stratification that advanced imaging techniques may hold the greatest promise, and for which MRI should be studied in future prospective trials.”