I want to congratulate Yoon et al. [1], who investigated the incidence and predictors of chemotherapy-induced left ventricular dysfunction (LVD) in patients with breast cancer. They reported that low body mass index, advanced cancer stage, and the use of trastuzumab were independent predictors of chemotherapy-induced LVD in patients with breast cancer. In addition to these findings, new serum markers were identified for prediction of trastuzumab-related cardiac dysfunction (TRCD) [2]. Zardavas et al. [3] explored the prognostic value of cardiac markers (troponins I and T, N-terminal prohormone of brain natriuretic peptide) to identify patients at increased risk for TRCD among those with early-stage human epidermal growth factor receptor 2-positive breast cancer receiving trastuzumab (HERA substudy). The authors reported that elevated troponin I or T before trastuzumab therapy is associated with increased risk for TRCD. Associated with this, a recent study by Beer et al. [4] investigated new biomarkers associated with doxorubicin- and trastuzumab-induced cancer therapeutics-related cardiac dysfunction (CTRCD) using high-throughput proteomic profiling; they found that high baseline immunoglobulin E levels are associated with a lower risk of CTRCD, highlighting the role of the immune system as a potential mediator of CTRCD. Thus, evaluation of the aforementioned serum markers may improve the identification of patients at increased risk for TRCD.