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MRI lacks  benefits over mammogram in staging  prior to breast conserving surgery, according to a study presented at San Antonio Breast Cancer Symposium.
Breast conserving surgery is not improved by the addition of MRI to other conventional staging assessments, according to a study presented at the  San Antonio Breast Cancer Symposium.

San Antonio Breast Cancer Symposium is the first Symposium presented by the CTRC, AACR, and the Baylor College of Medicine.  The driving force behind the new collaboration is the shared mission of the organizations to advance progress against breast cancer.

Women randomized to receive MRI as part of loco-regional staging before wide local excision were no more likely to avoid mastectomy and or reoperation than those who had the conventional mammogram, ultrasound, and biopsy for staging (P=0.7691), Phil Drew, M.D., of Hull York Medical School in Hull, England.

These findings from the first prospective randomized trial of MRI in this setting confirm the lack of benefit seen in prior retrospective studies, commented Monica Morrow, M.D., of Memorial Sloan-Kettering Cancer Center in New York.  Dr. Morrow recommended a minimal role for MRI in the newly diagnosed patient. As a result, the British National Health Service had Dr. Drew's group assess the new imaging technique in the multicenter, open-label COMICE trial.

The study included 1,623 women with biopsy-proven primary breast cancer who were scheduled for wide local excision based on triple assessment with mammogram, ultrasound, and biopsy. Participants were randomized to additional MR imaging.

For the primary endpoints, the MRI-assessed patients were more likely to go on to have mastectomy instead of the previously planned wide local excision (7.1 percent versus 1.2 percent) with no difference in reoperation rates (18.75 percent versus 19.33 percent, odds ratio 0.96, P=0.7691).   

The only significant predictors of reoperation were younger age and lobular cancer, not MRI. "We went hard on the data but didn't find anything at all that predicted benefit with MRI, including surgeons with low margins," Dr. Drew said.

At all stages the patients and physicians were informed of the MRI findings, which may have biased the trial results, Dr. Drew said.  Although the median size of the index lesion was identical across groups, MR-imaged patients tended to have larger excisions (70.55 versus 63.69 g, P=NS).

Given the National Health Service emphasis on cost-effective treatment, Dr. Drew said his group "tried very hard to find a difference in cost" but was surprised to find that none appeared. "The extra MR cost was not enough compared to other costs."

MRI had a relatively low effectiveness, and the positive predictive value was 61.8 percent, while the negative predictive value was 83.7 percent.  MRI changed management for 6.1% of patients, but 28% of multifocal disease was not confirmed pathologically.   MRI also correctly detected additional cancerous lesions in 4.8% of patients, which was not significant.

Source:  San Antonio Breast Cancer Symposium.