Abstract
Existing evidence suggests that preoperative breast magnetic resonance imaging (MRI) might not improve surgical outcomes in the general breast cancer population. To determine if patients differentially benefit from breast MRI, we examined surgical outcomes-initial mastectomy, reoperation, and final mastectomy rates-among patients grouped by histologic type. We identified women diagnosed with early-stage breast cancer from 2004 to 2007 in the SEER-Medicare dataset. We classified patients as having invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), mixed ductal/lobular carcinoma (IDLC) or other histologic type. Medicare claims were used to identify breast MRI and definitive surgeries during the initial surgical treatment episode. We used propensity score methods to account for the differential likelihood of exposure to MRI. Of the 20,332 patients who met our inclusion criteria for this study, 12.2 % had a preoperative breast MRI. Patients with ILC as compared to other histologic groups were most likely to receive MRI [OR 2.32; 95 % CI (2.02-2.67)]. In the propensity score-adjusted analyses, breast MRI was associated with an increased likelihood of an initial mastectomy for all patients and among all histologic subgroups. Among patients with ILC, having a breast MRI was associated with lower odds of a reoperation [OR 0.59; 95 % CI (0.40-0.86)], and an equal likelihood of a final mastectomy compared to similar patients without a breast MRI. Overall and among patients with IDC and IDLC, breast MRI was not significantly associated with a likelihood of a reoperation but was associated with greater odds of a final mastectomy. Our study provides evidence in support of the targeted use of preoperative breast MRI among patients with ILC to improve surgical planning; it does not provide evidence for the routine use of breast MRI among all newly diagnosed breast cancer patients or among patients with IDC.