The Impact of Preoperative Magnetic Resonance Imaging on Surgical Treatment and Outcomes for Ductal Carcinoma In Situ

Background: Although magnetic resonance imaging (MRI) is a useful imaging modality for invasive cancer, its role in preoperative surgical planning for ductal carcinoma in situ (DCIS) has not been established. We sought to determine whether preoperative MRI affects surgical treatment and outcomes in women with pure DCIS. Patients and Methods: We reviewed consecutive records of women diagnosed with pure DCIS on core biopsy between 2000 and 2007. Patient characteristics, surgical planning, and outcomes were compared between patients with and without preoperative MRI. Multivariable regression was performed to determine which covariates were independently associated with mastectomy or sentinel lymph node biopsy (SLNB). Results: Of 149 women diagnosed with DCIS, 38 underwent preoperative MRI. On univariate analysis, patients undergoing MRI were younger (50 years vs. 59 years; P < .001) and had larger DCIS size on final pathology (1.6 cm vs. 1.0 cm; P = .007) than those without MRI. Mastectomy and SLNB rates were significantly higher in the preoperative MRI group (45% vs. 14%, P < .001; and 47% vs. 23%, P = .004, respectively). However, there were no differences in number of re-excisions, margin status, and margin size between the two groups. On multivariate analysis, preoperative MRI and age were independently associated with mastectomy (OR, 3.16, P = .018; OR, 0.95, P = .031, respectively), while multifocality, size, and family history were not significant predictors. Conclusion: We found a strong association between preoperative MRI and mastectomy in women undergoing treatment for DCIS. Additional studies are needed to examine the increased rates of mastectomy as a possible consequence of preoperative MRI for DCIS.