Potential impact of cardiac dose-volume on acute cardiac toxicity following concurrent trastuzumab and radiotherapy

Purpose. - To analyse the risk factors associated with acute cardiotoxicity in HER2-positive breast cancer patients receiving concurrent trastuzumab and radiotherapy. Patients and methods. - Medical records of 45 breast cancer patients treated between 02/2009 and 0212011 by concurrent trastuzumab and radiotherapy were collected. Radiation was delivered to the conserved breast or chest wall with or without regional nodes. Dose prescription was 50 Gy in 25 fractions over five weeks with a tumor bed boost of 10 Gy in 5 fractions in breast conservation. Acute cardiotoxicity (grade >= 1) was defined using NCI-CTC v2.0. Doses to the heart and left ventricle were quantified. Results. - Median follow-up of left ventricular ejection fraction and clinical assessment from the completion of radiotherapy was 10 months (range: 3-27 months) and 25 months (range: 13-40 months), respectively. Ten (22.2%) and one (2.2%) of the 45 patients developed grade 1 and grade 2 cardiotoxicity, respectively. For 24 left-sided patients, the mean heart dose was significantly higher in those with cardiac events compared to those without (10.14 and 6.27 Gy, respectively; P < 0.05). A continuous increase of D-17-D-57 and V-10-V-15 of the heart and increase of D-40-D-80 and V-5-V-7 of the left ventricle were statistically significant in left-sided patients who developed cardiotoxicity compared with those who did not (P < 0.05). No significant relationship of dosimetric parameters of cardiac structures and cardiac events was found in right-sided patients. Conclusions. - Left-sided irradiation with increased low dose-volume and mean heart dose were associated with increased but reversible low-grade early cardiac toxicity after use of concurrent trastuzumab. (C) 2014 Societe francaise de radiotherapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.