Medical progress have made it possible to considerably improve the survival of children with an oncological disease. Currently, the survival rate increased to above 90 % in the most developed countries . This increase of childhood cancer survivors (CCS) asks us about their future and their quality of life. Assessing health related life quality , previous studies observe that in this particular population of patients, it is related to a poor physical capacity , physical activity level and many of these patients do not meet the activity level recommended by the world health organization due to fatigability and sedentary behaviours . In addition to these habits, the CCS are more susceptible to develop cardiovascular risk (CVR) leading to cardiovascular disease in adulthood and increases them mortality . Furthermore, CCS who have been experiencing hematopoietic stem cells transplantation (HSCT) are more susceptible to develop these CVR. In parallel with the common CVR, lower cardiopulmonary fitness assessed by cardiopulmonary exercise test (CPET) in the general population has been established as a major and independent CVR for cardiologic events.

Cardiopulmonary fitness assessed by maximal cardiopulmonary exercise test (CPET) allows physicians to measure metabolic response to maximal effort in a population that is known as VO2max. This domain of applied physiology permits a new way to approach the understanding of global health prognosis in chronic disease. For example, decrease of VO2max is involved in lower quality of life in patients with congenital heart disease. Cardiopulmonary exercise test for VO2max exploration has been demonstrated feasible in child patients with leukemia or other tumors after intensive chemotherapy, prior to HSCT.

Assessment of cardiopulmonary fitness in CCS is already described in previous studies, but this study aimed to compare a maximal CPET assessment on a large childhood cancer survivors cohort with healthy control, on a quite young cohort, during the oncologic follow up and find out its determinants.

This is a controlled, monocentric, cross-sectional study conducted in a tertiary care center for oncologic disease in children (Montpellier University Hospital, France) was carried out between November 2010 and November 2020.

Two groups were identified: CCS group and control group.

Inclusion criteria for CCS group :

• aged between 5 and 25 years old,
• having been complete a full regimen for oncological disease and considered in remission at the end of treatment. Remission was considered in absence of relapse or new treatment initiated before the CPET end point.

Inclusion criteria for control group :

• children referred for a nonsevere functional symptom linked to exercise (murmur, palpitation or dyspnoea) or for a medical sports certificate.
• completely normal check-up, including physical examination, ECG, echocardiography and spirometry.

Exclusion criteria for control group:

• Children with any chronic disease, medical condition (cardiac, neurological, respiratory, muscular or renal)
• Children with any medical treatment
• Children requiring any further specialised medical consultation

• CCS having been complete a full regimen for oncological disease and considered in remission at the end of treatment
• Controlled children with completely normal check-up, including physical examination, ECG, echocardiography and spirometry

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