Obesity during and after Treatment for Childhood Cancer.

Obesity is a common complication of treatment for some childhood cancers, particularly acute lymphoblastic leukaemia (ALL) and craniopharyngioma. Evidence-based guidance is available for the general paediatric population on the diagnosis, aetiology, consequences, prevention and treatment of obesity, and this should be considered as the starting point for considering such issues in patients with malignancy. In ALL, a high proportion of patients show rapid and excessive weight gain soon after diagnosis which originates partly in lifestyle, in particular via markedly reduced levels of physical activity. Good evidence on risk factors for obesity in ALL is available, and the natural history and aetiology of obesity in ALL are now fairly well understood, while for craniopharyngioma the natural history is reasonably well understood. Understanding the natural history and aetiology of obesity should facilitate preventive interventions in the future. Evidence on preventive interventions is required urgently, and it should focus on promotion of a reduction in sedentary behaviour and increases in physical activity. Such interventions should be helpful in obesity prevention, but could also have a wide range of additional benefits in the prevention or amelioration of other late effects of treatment.