New data answer fears about impact of breast MRI

New data presented at the 2007 RSNA meeting may help ease fears that use of preoperative breast MRI will hike mastectomy rates and cause delays in time to surgery.

Greater utilization of dynamic contrast-enhanced MRI at the University of California, San Diego over a six-year period helped improve surgery planning for tough cases without hiking mastectomy rates, according to a retrospective study by Dr. Christopher Comstock and colleagues.

The UCSD study evaluated the effects of preoperative MRI on surgery in terms of delays and margins on patients with biopsy-proven breast cancer who underwent surgery at UCSD from 2000 to 2006. In the first two years of the study period, only one patient had preoperative MRI, but by the latter part of 2003, 40% to 50% of surgical patients were undergoing the imaging study.

Critics say preoperative MRI can increase mastectomy rates and cause delays in surgery due to clinically insignificant disease detected by MRI. They are less likely to cite lumpectomy's positive margin rates, which range from 30% to 40% nationwide and result in multiple surgeries to obtain clear margins. At UCSD, the lumpectomy negative margin rate was higher for those who had preoperative MRI (80%) versus those who did not (75%).

"This may not seem like a big difference, but those who underwent preoperative MRI had larger or more complicated cancers or parenchymal patterns," Comstock said.

Furthermore, lumpectomy negative margin rates reached 90% by 2006 and there was no significant difference in the time to surgery. Despite increasing utilization of preoperative MRI, mastectomy rates remained stable throughout most of the study period, thanks to good communication between specialists and effective counseling of patients, Comstock reported.