Advances in cancer therapies have led to increasing numbers of adults previously treated for a pediatric malignancy, many of whom experience late adverse health-related sequelae and are at risk for developing chronic conditions related to their prior therapy. The epidemiology of many end-organ toxicities has been described, yet the pathophysiologic mechanisms of injury are incompletely understood. One mechanism may be damage to the circulatory system, in particular the endothelial layer, initiating an inflammatory state leading to dysfunction and premature atherosclerotic disease. This process may begin and significantly progress in a sub-clinical nature for many years prior to manifesting as a cardio- or cerebrovascular event. Using established and novel biomarkers predictive of atherosclerotic disease combined with unique measurements of vascular function, this study will assess pre-clinical vascular disease in a population of childhood and adolescent cancer survivors. The goals of this project are to investigate the effects of cancer therapy on the vascular system and acquire new knowledge with which to risk-stratify survivors and plan interventional studies to prevent or reduce premature vascular morbidity and mortality.