Abstract OT3-02-01: Accuracy of split dynamic magnetic resonance imaging in locally advanced breast cancer during neoadjuvant aromatase inhibitor therapy

Abstract

Abstract Background: Neoadjuvant aromatase inhibitor (AI) therapy is an efficient treatment option in highly selected postmenopausal patients with strongly hormone receptor positive locally advanced breast cancer (LABC) to obtain a tumor downstaging prior to breast surgery with acceptable response rates when standard chemotherapy is not indicated. The tumor response evaluation during therapy is of crucial importance but often-suboptimal using standard procedures. Contrast enhanced magnetic resonance imaging (MRI) is currently the most sensitive of the available imaging modalities in detection and characterization of a breast tumor before and during neoadjuvant therapy. The sub-study presented here was designed to test a novel technique called split dynamic MRI in which a high temporal resolution multi-echo sequence is interleaved with a standard dynamic high spatial resolution sequence during a single bolus injection. This method has an advantage over the current dynamic MRI, as it provides extensive information about both structural and functional assessment of the tumor through quantitative evaluation of both T1- and T2 *- weighted characteristics. Trial Design: NEO-LET-EXE is a neoadjuvant, randomized, open-label, intra-patient cross-over trial. Eligibility criteria: Postmenopausal patients diagnosed with estrogen receptor (ER) positive (≥10%) breast cancer and HER-2 negative LABC not suitable for neoadjuvant chemotherapy are eligible for the study. Specific aims: A 1.5T scanner is used to obtain and investigate the clinical utility and diagnostic accuracy of T1_T2 multi-echo EPI and dynamic THRIVE sequences during a single injection of contrast agent at baseline and following AI therapy with either letrozole or exemestane for at least two months followed by the alternative drug for another two months. The study clarifies the feasibility of split dynamic MRI method as a tool for predict treatment response, analyse biological behaviour and tumor aggressiveness. In addition, our findings will allow quantitative comparisons of the intra-tumor effects of aromatase inhibitors with clinical breast evaluations for prediction of postoperative pathologic complete response. Statistical methods: Quantitative analysis will be performed with pharmacokinetic modelling on T1-weighted images and estimation of maximum peak change in R2* images using receiver operating characteristic (ROC) analysis. Two radiologists are interpreting high spatial resolution data. Mann-Whitney tests will be used to determine the parameters ability for establishing and characterization of the tumor. Present accrual and target accrual: The study has currently enrolled 55 patients (of planned 100) at the Akershus University Hospital, Norway. Accrual is planned to be completed within the next 2 years. Our early experience with the applied technology will be presented and discussed. Citation Format: Joana Reis. Accuracy of split dynamic magnetic resonance imaging in locally advanced breast cancer during neoadjuvant aromatase inhibitor therapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT3-02-01.