Association of Routine Pretreatment Magnetic Resonance Imaging with Time to Surgery, Mastectomy Rate, and Margin Status

Background: The benefit of breast MRI for newly diagnosed breast cancer patients is uncertain. This study characterizes those receiving MRI versus those who did not, and reports on their short-term surgical outcomes, including time to operation, margin status, and mastectomy rate. Study Design: All patients seen in a multidisciplinary breast cancer clinic from July 2004 to December 2006 were retrospectively reviewed. Patients were evaluated by a radiologist, a pathologist, and surgical, radiation, and medical oncologists. Results: Among 577 patients, 130 had pretreatment MRIs. MRI use increased from 2004 (referent, 13%) versus 2005 (24%, p = 0.014) and 2006 (27%, p = 0.002). Patients having MRIs were younger (52.5 versus 59.0 years, p < 0.001), but its use was not associated with preoperative chemotherapy, family history of breast or ovarian cancer, presentation, or tumor features. MRI was associated with a 22.4-day delay in pretreatment evaluation (p = 0.011). Breast conserving therapy (BCT) was attempted in 320 of 419 patients with complete surgical data. The odds ratio for mastectomy, controlling for T size and stage, was 1.80 after MRI versus no MRI (p = 0.024). Patients having MRIs did not have fewer positive margins at lumpectomy (21.6% MRI versus 13.8% no MRI, p = 0.20), or conversions from BCT to mastectomy (9.8% MRI versus 5.9% no MRI, p = 0.35). Conclusions: Breast MRI use was not confined to any particular patient group. MRI use was not associated with improved margin status or BCT attempts, but was associated with a treatment delay and increased mastectomy rate. Without evidence of improved oncologic outcomes as a result, our study does not support the routine use of MRI to select patients or facilitate the performance of BCT.