The goal of this prospective interventional study is to improve the detection of subclinical chronic Cancer Therapy-Related Cardiovascular Toxicity (CTRCT) and evaluate the added value of advanced cardioechography, ergospirometry, and specific biomarkers in pediatric cancer survivors (aged 2 to 25) who received potentially cardiotoxic treatments (chemotherapy/thoracic radiotherapy). The main questions it aims to answer are:
* Can advanced echocardiography (including strain and myocardial work), ECG, and ergospirometry effectively diagnose earlier subclinical cardiac impairment in this population?
* What is the prevalence of cardiovascular risk factors (including physical activity levels and biological markers like proBNP/troponins)
* Can new genetic or biological markers be identified to help optimizing the detection of CTRCT?
At time of follow-up, if they agree, participants will:
* Complete validated questionnaires regarding quality of life, physical activity, and sedentary behavior.
* Undergo a cardiopulmonary exercise test (ergospirometry) for those aged over 8 years.
* Wear an accelerometer (ActiGraph GT3X) for 7 consecutive days to monitor physical activity.
* Provide an additional blood sample during routine follow-up for the creation of a biobank dedicated to analyzing markers of senescence, fibrosis, apoptosis, and genetic polymorphisms.