Lymphomas are cancers of the lymphatic system, which affect nearly 200 children each year in France. In children under 15, the most common type of lymphoma is "non-Hodgkin's". In adolescents and adults, it is more about Hodgkin lymphoma. During the last decade, efforts have mainly focused on reducing the volumes and doses of radiation and on the gradual elimination of the most aggressive drugs that generate sequelae. Overall 5-year survival is around 70%, which means that almost one in 3 children will not be cured.