Abstract P4-02-11: Value of magnetic resonance imaging in preoperative predicting tumor extent in each subtypes of breast cancer

Abstract

Background: It is well known that patients with triple-negative breast cancer (TNBC) have a high risk of local tumor recurrence in ipsilateral breast. To know the additional value of breast magnetic resonance imaging (MRI) in preoperative prediction of tumor extent for TNBC, we tested the accuracy of MRI in correlation with pathologic tumor size according to subtypes. In addition, we investigated the margin-positive rates by subtypes among the patients receiving breast-conservative surgery (BCS). Methods: We retrospectively identified patients with invasive breast cancer who had preoperative breast MRI and ultrasound between 2011 and 2014. We excluded patients having large tumor more than 5cm or multiple tumors. Patients were classified into 4 subtypes (luminal A, luminal B/HER2, HER2, triple-negative breast cancer (TNBC)) based on the immunohistochemistry. Lin's concordance correlation coefficient was used to measure the agreement between the MRI or ultrasound and tumor extent. Also, patients were classified into three groups according to the accuracy of MRI in correlation with tumor extent (concordance, underestimation, and overestimation). Tumor extent was defined as pathologic tumor size including in situ carcinoma. Results: In a total of 589 patients, 397(67.4%) women received BCS. Means of tumor size were 1.99 ± 0.91 cm by pathologic review, 1.91 ± 1.01 cm by MRI, and 1.76 ± 0.92 cm by ultrasonography, respectively. Correlation analysis revealed a similar concordance rate between MRI and ultrasound to pathologic tumor size (r= 0.622 and 0.573). Lin's concordance analysis showed that MRI showed more significant correlation with pathologic tumor size than ultrasound in patients with TNBC (r= 0.735 VS 0.593, p=0.0052). However, the proportion of concordant group did not differ significantly according to subtypes (p=0.279). Conclusions: Our findings suggest that preoperative MRI does not increase the accuracy in predicting tumor extent or reduce the margin-positive rates in breast cancer. Citation Format: Yang BS, Lee HW, Park JT, Lee HM, Ahn SG, Jeong J. Value of magnetic resonance imaging in preoperative predicting tumor extent in each subtypes of breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-02-11.