Beyond The Scalpel: Does Preoperative MRI Lower Re-Excision Rates?

The Shave/Shave2 trials were large multicenter trials including patients with stage 0-3 breast cancer. The use of preop MRI was at the discretion of the surgeon. These researchers evaluated whether preoperative MRI was associated with margin status prior to randomization (Chapgar et al. NEJM 1015, 6: 503-10 epub). The results of the Shaved margin trials showed that those who had shaved margins after initial excision had a significantly lower rate of positive margins (19% versus 34%) as well as second surgeries for margin clearance (10% versus 21%). There was no difference in complications between the two groups.

631 patients participated in the Shave 1 /2 study. The median age was 64. A preoperative MRI was performed in 193 of those enlisted (30.6%). The median tumor size was 1.3 cm. 26.1% of patients had palpable tumors and 6.5 received neoadjuvant chemotherapy. Lobular histology was the primary diagnosis and 7% and an extensive intraductal component was present in 32.8%.

Results

Those patients who underwent a preoperative MRI were less likely to have a positive margin (31.1% versus 38.8%), although this difference was not statistically significant. On multivariate analysis, controlling for patient and tumor factors, utilization of preoperative MRI was nonsignificant but was a significant factor in predicting margin status. Rather, age, and tumor size were the only factors associated with margin status.

In conclusion, the authors suggest that preop MRI is not associated with margin status; rather, patient age and tumor size are the associated factors.

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Dr. Alan Stolier, MD, FACS, clinical breast oncologist, shares his expert medical perspective with a series of educational and scientific articles.