Though often used to determine the extent of cancer in women with dense breast tissue, a new study casts additional doubt on the usefulness of pre-operative magnetic resonance imaging in preventing further surgery among women undergoing full or partial mastectomy.
In fact, MRI tends to overestimate the extent of the disease, according to the research published in Archives of Surgery. Mastectomies later were determined to be unnecessary in one-quarter of the patients who underwent the procedures.
"The selective use of preoperative MR imaging to decrease reoperation in women with breast cancer is not supported by these data," wrote Jan H. Wong, M.D., of East Carolina University in Greenville, N.C., and colleagues.
The study focused on the patients of one of Wong's East Carolina colleagues, Lisa Bellin, M.D., who were treated between 2006 and 2010. Of the 313 patients in the study, 120 underwent preoperative MR imaging based on the recommendations of a multidisciplinary breast tumor board at the institution, reports MedPage Today.
Those who underwent MRI were more likely to be younger and Caucasian, to have dense breast tissue and larger tumors, the authors note.
Reoperation rates, however, were not significantly different between the two groups. In each group, 8.3 percent later had full mastectomy; 10.8 percent of the preoperative MRI group and 9.3 percent of those who did not have preoperative MRI later had partial mastectomy; and 80.8 percent of the preoperative MRI group and 82.4 percent of the no preoperative MRI group had no further surgery.
The MRIs also produced some false negatives. Eight patients whose MRIs indicated unifocal tumors actually had more widespread disease.
Though reflecting the practice of one surgeon at one institution, the authors noted their findings were consistent with several other population-based analyses. They conceded, however, that there are situations in which MRI scans would be indicated.
Despite their expense, MRI scans have become common for women with breast cancer. In accompanying commentary, Sharon Lum, M.D., of Loma Linda University in California, noted the growing body of evidence that MRI, despite its presumed increased sensitivity, has questionable value in preventing further surgery. She called the study another reason to adhere to evidence-based medicine and called on physicians to alter their practice responsibly "to reflect data, rather than fear."
A recent study in the Journal of the National Cancer Institute showing more widespread use of imaging in late-stage cancer patients included a call for better clinical guidelines on its use.
Yet despite the debate over recommendations for mammography, a review of major breast cancer screening programs in Europe has concluded that the benefits for women ages 50 to 69 outweigh the risk of overdiagnosis.