Context: Sport and physical activity during and after cancer treatment can improve fitness and social inclusion in adults. In children, although early studies show interesting results, conclusive data are lacking. A preliminary evaluation conducted in a dozen children following a physical training program showed a significant improvement in endurance, muscle tone, overall self-esteem, sports skills and self-perceived strength. The investigators then want to evaluate the health of a group of children during treat cancer that physical activities adapted compared to children who did not practice.

Objective: Measuring the impact of physical activity program on health of children and adolescents with cancer with improved physical, psychological health, social reintegration and reduced time hospitalization.

Method and Design: The study plans to include 90 children from the pediatric hematology - oncology department of the La Timone CHU, aged 5-19 years with cancer, over a period of 18 months.

This is a randomized controlled open trial open with a stratified distribution. Children will be randomized between two arms - Arm A (Experimental - Immediate Program): the child follows the physical activity program for a period of 18 months, as soon as his medical condition permits. - Arm B (Control - Delayed Program): the child does not participate to the program during the first 6 months, and he joins the delayed program late after 6 months. Each child integrates the physical program for a period of one year.

Regardless of the randomization arm, the child performs the initial tests, the intermediate tests at 6 and 12 months and final tests at 18 months. Follow-up physical testing will be performed at 3 and 9 months.

The physical activity program includes a minimum of 30 days of activities per 6 months (4days/month and a long stay). The child practice between 2 to 4 hours of activity per day.

The investigators aim at demonstrating a difference of 50 meters on the total walked distance during the endurance test in the experimental group as compared to the control group after 6 months of program.

Inclusion Criteria:

• Patient with malignant disease
• Supported in service pediatric hematology-oncology child Timone hospital in Marseille.
• Age ≥ 5 years and ≤ 19 years
• No medical-cons to the practice of physical activity

Exclusion Criteria:

• Life expectancy less than 18 months.
• Inability to comply with follow-up study for geographical, social or psychological.
• Length of stay less than 18 months, for children living outside mainland
• Not understanding of the French language
• Prior Participation in physical activity program