Adjuvant Trastuzumab Emtansine (T-DM1) and Concurrent Radiotherapy for Residual Invasive HER2-positive Breast Cancer: Single-center Preliminary Results.

Abstract

The treatment of nonmetastatic HER2-positive breast cancer with residual invasive disease using concurrent Trastuzumab emtansine (T-DM1) and radiotherapy appears to be an effective option. Our aim was to evaluate the acute side effects of this treatment regime. Fourteen patients were treated between March 2019 and April 2020 concurrent T-DM1 and radiotherapy. Left ventricular ejection fraction was assessed at baseline, before and after radiotherapy. All toxicities were evaluated using Common Terminology Criteria of Adverse Events (CTCAE) version 3.0. The median age was 55 years (range 36 to 72). All patients received total dose of 50 Gy for the breast/ chest wall, 10 patients got lymph node irradiation, 4 patients received an additional tumor bed boost. The most common side effect was grade 1 radiodermatitis. A reversible grade 2 left ventricular ejection fraction decrease occurred in 2 patients. During our examination 3 patients showed alanine aminotransferases increase after the cycle 4 of T-DM1, 1 patient had grade 1, 1 patient grade 2, and 1 patient grade 3 alanine aminotransferase increases. The acute toxicity rate especially focusing on skin and cardiac toxicity were assumed acceptable in our cohort. To safely administer this concomitant treatment, further examination and prospective data are needed.