MRI of the breast before and after primary systemic therapy correlates with histopathological tumor size in patients with locally advanced breast cancer (LABC)

Abstract

507 Background: Primary systemic therapy (PST) is a widely accepted preoperative treatment for patients with locally advanced breast cancer (LABC). Different authors beside our study-group showed that MRI is a sensitive method in describing the remaining size of an invasive breast lesion after PST. The established methods for measuring the size of lesions and monitoring the tumour-response to chemotherapy are clinical palpation, mammography and ultrasound, but specificity of these methods is unsatisfactory. Our prospective data is to clarify the accuracy of MRI in monitoring the tumour-response to PST is presented. Methods: 207 female patients (range of age: 26a- 78a) with LABC (cT2 – cT4) were examined with dynamic contrast enhanced MRI after PST. 173 (84%) patients have had MRI examination before and after PST. 145 (70%) patients had a ductal-invasive, 48 (23%) patients a lobular-invasive carcinoma. 70 (34%) patients were treated with sequential anthracyclin- and taxan-based chemotherapy and 137(66%) with only anthracyclin based chemotherapy. 51% patients were premenopausal. 70% had an ER-positive tumour. The measure of tumour-response to PST was graded in partial response (PR: >50% of tumour reduction mm2), no change (NC: <50%) and complete response (CR: no evidence of residual tumour-cells). Results: Comparing tumour-size measured by MRI before and after PST 119 (69 %) of the patients had PR and 25 (14.5%) CR. The histological tumour- size after PST strongly correlated with the size measured by MRI r = 0,758 (pâ€1 0.001). Analyzing the tumour-types ductal-invasive carcinomas were significant (p<0.001) better to monitor than lobular-invasive types (r=0.824/r=0.210). Conclusions: preoperative MRI seems to be a helpful tool in estimating the efficacy of the tumour-response to chemotherapy and for the operative planning in the patients with LABC after PST, especially for ductal-invasive tumours. No significant financial relationships to disclose.