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.