To the editor,

I want to congratulate Lee and colleagues for their article [1] in which they investigated factors for the time to occur trastuzumab-induced cardiotoxicity. They showed that body mass index ≥ 23 kg/m2, LVEF < 62.5%, and anthracycline-based chemotherapy were associated with time to trastuzumab-induced cardiotoxicity. The authors did not mention other predictive markers for trastuzumab-induced cardiotoxicity. Zardavas et al. [2] explored the prognostic value of cardiac markers to identify patients at increased risk for trastuzumab-induced cardiotoxicity in patients with early-stage HER2-positive breast cancer receiving trastuzumab (HERA substudy). The authors reported that elevated troponin I or T before trastuzumab is associated with increased trastuzumab-induced cardiotoxicity. Beer et al. [3] investigated new biomarkers associated with doxorubicin- and trastuzumab-induced cancer therapeutics-related cardiac dysfunction (CTRCD) using high-throughput proteomic profiling, and they found that high baseline immunoglobulin (Ig) E levels are associated with a lower risk of CTRCD, pointing out the immune system as a potential mediator of CTRCD. Taken all together, evaluation of baseline serum Ig E and troponin I or T levels in addition to aforementioned cardiac risk factors may clearly identify patients at increased risk for trastuzumab-induced cardiotoxicity.