Top Line: We saw a few weeks ago that preoperative MRI was felt to be beneficial for treatment planning in women with DCIS in an observational study.
The Study: In particular, MRI helped patients and surgeons make confident surgical decisions based on the extent of disease and chances of successful resection. Those are pretty soft outcomes, though, especially for the French. In the IRCIS trial, women with DCIS undergoing planned breast conservation were randomized +/- to pre-op MRI to determine if there was a reduction in the re-intervention rate. In the MRI arm, 25% of patients were found to have an additional mammographically occult lesion, with nearly half of those in the opposite breast. But only one-third of these lesions were cancerous and even those were mostly in situ. At 6 months, the addition of pre-op MRI reduced the reintervention rate from 27→ 20%, which was a 26% relative reduction. As a comparison, obtaining shave margins halves in reintervention rate from 21→ 10% at a fraction of the cost. MRI also failed to significantly alter the mastectomy rate.
Bottom Line: Obtaining routine breast MRI in women with DCIS who are candidates for breast conservation based on standard imaging work-up does not significantly reduce the rate of reintervention. | Balleyguier, J Clin Oncol 2019


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