Breast Cancer Recurrence in Patients with Newly Diagnosed Breast Cancer without and with Preoperative MR Imaging: A Matched Cohort Study

To compare breast cancer disease-free survival (DFS) outcomes of patients with newly diagnosed breast cancer without and with preoperative magnetic resonance (MR) imaging. MATERIALS AND METHODS This study was approved by an institutional review board, and informed consent was waived. From 2004 to 2009 (unilateral MR imaging from 2004 to 2006 vs bilateral MR imaging from 2007 to 2009), patients with breast cancer without preoperative MR imaging (no MR imaging group) were matched with those with preoperative MR imaging (MR imaging group) according to age, histologic grade, nuclear grade, tumor size, nodal status, stage, hormone receptor status, Ki-67 status, molecular subtype, and lymphovascular invasion. Survival analysis was performed by using Kaplan-Meier estimates. A marginal model was used to evaluate the effect of preoperative MR imaging on DFS.A total of 371 patient pairs from the unilateral imaging period and 97 patient pairs from the bilateral imaging period were matched. During the unilateral imaging period, the MR imaging group had better local-regional recurrence DFS (hazard ratio [HR], 0.33; 95% confidence interval [CI]: 0.12, 0.91; P = .032) than did the no MR imaging group; however, no difference was found for contralateral breast (P = .440) or distant recurrence (P = .515) DFS. During the bilateral imaging period, the MR imaging group had better contralateral breast cancer DFS (HR, 0.03; 95% CI: 0.04, 0.21; P < .001) than the no MR imaging group; however, no difference was found for local-regional (P = .180) or distant recurrence (P = .178) DFS.Preoperative bilateral breast MR imaging for staging of breast cancer was associated with a reduced risk of contralateral breast recurrence; however, no observed reduction in risk of local-regional or distant recurrence was shown.