Regular advances in cancer treatment have dramatically improved the prognosis of children and adolescents with acute leukemia (AL), raising with a great acuity the problem of the late physical side effects, social integration, quality of life of the patients and their family as well as identification of the determinants of these outcomes. Large nationwide and international cohorts developed in general population (I4C, EPIC ELF…) are restricted to the study of childhood cancers occurrence. In addition, the national registries (French, European) of childhood cancers are designed to evaluate incidence and mortality, but not to produce individual detailed data on the follow-up and outcome of these children. Answering these questions supposes a comprehensive multidisciplinary approach resting on prospective cohorts of cancer survivors, specifically exploring the outcome of these children. These cohorts allow to identify prognostic factors of the health condition and social integration, and to propose adapted strategies of follow-up. The Childhood Cancer Survivor Study (CCSS), which remains the most important study, only concerns the North-American populations and rests on a self-reported follow-up assessment. In France, the LEA study, initiated in 2004 could answer some of these questions, but the representativeness and the size of the population (study initially limited to two areas PACA-Corsica and Lorraine) remain insufficient to study uncommon events. Similar approaches are conducted in Europe trough the broad collaborative Pancare network, to which the LEA program is associated.