Screening and intervention for treatment-related cardiac dysfunction in childhood cancer survivors.

Abstract

10.2217/FON.15.108 © 2015 Future Medicine Ltd During the past four decades, marked advances have been made in the treatment of childhood cancers, such that long-term survival is an expected outcome for many children diagnosed with cancer today [1]. However, improvements in outcome have come at a cost. It is estimated that nearly a third of all childhood cancer survivors will develop a severe or life-threatening health condition years after completion of cancerdirected therapy [2]; these include second cancers, endocrinopathies, neurosensory impairment and cardiovascular disease [2]. Outcomes following onset of cardiovascular disease are especially poor; 5-year overall survival is less than 50% [3], emphasizing the need to develop early screening and prevention strategies in survivors at highest risk of developing cardiovascular disease. Research on survivorship issues has revealed a clear association between certain therapeutic exposures such as anthracycline chemotherapy and/or mediastinal radiation and risk of cardiovascular complications such as heart failure [4]. In these survivors, there is often a long latency between initial exposure to cardiotoxic therapies and onset of clinically overt heart disease [4]. This period is characterized by the development of asymptomatic systolic and/or diastolic cardiomyopathy that can be detected using a variety of imaging modalities [4,5]. Radionuclide angiography (multigated acquisition scan and radionuclide ventriculography) was historically considered the gold standard for assessment of cardiac function [4,5]. However, exposure to ionizing radiation, along with a limited ability to detect structural abnormalities and early cardiac dysfunction, has limited its use in childhood cancer survivors [4,5]. 2D echocardiography offers a readily available assessment of both structure and function without exposure to radiation, and has therefore been widely used to follow childhood cancer survivors. [4,5] Frequently measured echocardiographic parameters of cardiac function include ejection fraction, shortening fraction, velocity of fiber shortening corrected for heart rate, stress–velocity index, left ventricular end-systolic wall stress and more subtle measures of diastolic function [4–6]. More recently, cardiac MRI has emerged as a sensitive and reproducible alternative to echocardiography in nononcology populations and cancer survivors [7,8]. However, despite its diagnostic advantages, higher cost and limited availability impede its use for routine screening. Consequently, current guidelines continue to recommend 2D echocardiography as the screening modality of choice for childhood cancer survivors [6]. COMMENTARY Special Focus Issue: Cardio-oncology