Abstract P2-13-04: The role of preoperative MRI in negative margins after breast conserving surgery in patients with invasive breast cancer or purely DCIS
Authors: Vos Elvira L , Voogd Adri C , Verhoef Cornelis , Obdeijn Inge-Marie , Koppert Linetta B 
Published: May 2015

Abstract
Introduction Clinical benefit of preoperative MRI in invasive breast cancer (IBC) patients and patients with purely ductal carcinoma-in-situ (DCIS) remains controversial. We aimed to study the role of preoperative MRI in negative margins after breast conserving surgery (BCS) and reexcision rate in a large population-based cohort.
Methods Retrospective analyses were performed in women diagnosed with IBC and purely DCIS and surgically treated between 2011-2013 extracted from the Eindhoven Cancer Registry. Patients were excluded in case of: neo-adjuvant systemic therapy, (clinical or pathological) tumor stadium T4, distant metastasis, and unknown resection margin status. According to preoperative MRI use, the study population was divided into a non-MRI and MRI group. All multivariable analyses were adjusted for baseline differences between non-MRI and MRI group with P&lt;0.1. No information was available on the exact reason to perform MRI preoperatively in these patients.
Results A total of 3,116 patients were eligible of which 2,238 (71.8%) patients were treated by breast conserving surgery (BCS) and included for analyses. Preoperative MRI was performed in 592 (30.6%) IBC patients and 55 (18.3%) DCIS patients. In IBC patients, differences in non-MRI and MRI group were: median age (62 vs 58), histology (lobular type in 5.7% vs 24.5%), median tumor size (13 mm vs 15 mm), her2neu receptor status and specific tumor locations. Median (interquartile range) time between diagnosis and surgery in the non-MRI and MRI group were 21 (16-28) and 31 (22-40) days respectively (univariable and multivariable P&lt;0.001). Negative margin was attained in 1,135 (84.4%) and 489 (82.6%) patients respectively (OR 0.88 95%CI 0.68-1.14 P=0.326). After adjustment for baseline differences and for factors associated with negative margin with P&lt;0.1 (i.e. histology, tumor size, differentiation grade, progesterone receptor %, her2neu receptor status, regional lymph node stadium, and tumor location) MRI use was not associated with negative margin (OR 1.09 95%CI 0.81-1.45 P=0.587). Reexcision was performed in 96 (7.1%) and 62 (10.5%) patients (P=0.013). In case reexcision was needed, conversion to mastectomy occurred in 32 (2.4%) vs 20 (3.4%) patients (P=0.210). In patients with purely DCIS, only median age differed in non-MRI and MRI group (61 vs 57). Median (interquartile range) time between diagnosis and surgery in the non-MRI and MRI group were 22 (16-31) and 35 (23-49) days respectively (univariable P&lt;0.001 and multivariable P=0.024). Negative margin was attained in 197 (80.1%) and 42 (76.4%) patients respectively (OR 0.80 95%CI 0.40-1.61 P=0.538). After adjustment for baseline differences and for factors associated with negative margin with P&lt;0.1 (i.e. differentiation grade and tumor location) MRI use was not associated with negative margin (OR 1.51 95%CI 0.72-3.16 P=0.280). Reexcision was performed in 39 (15.9) and 10 (18.2) (P=0.672). In case reexcision was needed, conversion to mastectomy occurred in 12 (4.9%) vs 3 (5.5%) patients (P=0.859).
Conclusion In both IBC and DCIS patients, preoperative MRI delayed time between diagnosis and surgery, but was not associated with a higher percentage of negative margins after BCS.
Citation Format: Elvira L Vos, Adri C Voogd, Cornelis Verhoef, Inge-Marie Obdeijn, Linetta B Koppert. The role of preoperative MRI in negative margins after breast conserving surgery in patients with invasive breast cancer or purely DCIS [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-13-04.