Background Child years cancer survivors are a growing population at risk for poor cardiac outcomes. were much like siblings in cardiovascular N-desMethyl EnzalutaMide risk steps but experienced poorer vascular health as measured by reactive hyperemia index (survivor RHI 1.54 vs sibling 1.77 p=0.0474). Conclusion This study reveals that even among survivors who are comparable to their healthy siblings in other traditional cardiovascular risks there is evidence of poorer vascular health. Introduction Improved remedy rates for child years cancer has led to a growing populace of survivors who are at risk for long-term complications from their disease and treatment including high risk for accelerated atherosclerosis 1. According to the Child years Cancer Survivor Study a landmark cohort study childhood malignancy survivors have more than 8 occasions increased mortality risk (Standardized Mortality Ratio [SMR]= 8.4; 95% CI 8.0 – 8.7) than the US general populace of the same age 12 months and sex due in large part to pulmonary and cardiac complications 2. Leukemia is the most frequently diagnosed childhood malignancy and acute lymphoid leukemia (ALL) is the most common form. Improved treatments have lead to an impressive five-year survival for childhood ALL of 88.5% 3 yet these survivors have a 4.2 SMR (95% CI 2.3-6.9) due to cardiac causes2. Treatment with cardio harmful chemotherapy and radiation in addition to the development of cardiovascular disease (CVD) risk factors after treatment are known to impact cardiac outcomes for malignancy survivors4-9. Vascular endothelium plays a key role in the N-desMethyl EnzalutaMide regulation of vascular health and based on findings in otherwise healthy children it is believed that impaired endothelial function in child years may be the initial step in the pathogenesis of atherosclerosis10-12. The release of nitric oxide (NO) from your endothelium is a key factor in maintaining healthy vascular homeostatsis and measurement of NO response has become an important predictor of cardiovascular health13-15 . Circulation mediated dilatation (FMD) is used to assess endothelial health via NO release and subsequent dilation in response to shear stress caused by occlusion of blood flow. The response of blood vessels to this transient ischemia and the producing reactive hyperemia state was first explained by Celermajer et al (1992) as a method of identifying atherosclerosis risk in adults and children16. In the beginning FMD assessment required ultrasound N-desMethyl EnzalutaMide measurement of intima-media thickness (IMT) at rest and during reactive hyperemia this technique is highly operator dependent and technically challenging17. More recent developments in technology include the assessment of reactive hyperemic response via peripheral artery tonometry (PAT). PAT uses automated measurement of reactive hyperemic index with fingertip plethysmography and has been validated by correlation with brachial artery ultrasound 18 and standard N-desMethyl EnzalutaMide cardiovascular risk factors19. Pediatric studies including diabetic and healthy populations have shown PAT technology to be useful in evaluating N-desMethyl EnzalutaMide endothelial health N-desMethyl EnzalutaMide in more youthful populations20 21 To date research has focused predominantly on identifying DcR2 risk factors associated with cardiovascular disease or changes in vascular health in adult survivors of child years cancer. Acknowledgement of early changes in vascular function in child malignancy survivors may allow healthcare providers to identify and intervene earlier in children most at risk for poor cardiac outcomes. This study examines the vascular health of child years ALL survivors earlier (while still in child years) than previously reported in the literature and utilizes a sibling comparison group to control for potential environmental and genetic contributors to vascular health. The primary aim of this pilot study was to evaluate endothelial function using peripheral artery tonometry in child years ALL survivors and compare them to healthy sibling controls. Materials and Methods A convenience sample of ALL survivors and healthy siblings (control group) were recruited from an established survivorship program via flyers mailed or distributed to parents during routine follow-up visits..