The proposed study will rigorously evaluate the usefulness of serial determinations of tissue Doppler imaging, cTn-T and NT-BNP for very early identification of anthracycline-related myocardial injury. Demonstration that one or more of these markers identifies subclinical myocardial damage and that biomarker or tissue Doppler imaging parameters exhibit a dose-response relationship with cumulative doxorubicin dose would facilitate intervention trials in patients at risk for anthracycline cardiomyopathy.