Malnutrition in pediatric oncology is considered common, and this diagnosis may be underestimated according to the evaluation method. Causes of nutritional problems (malnutrition, overweight and obesity) are multiple and dynamic, and may vary according to different stages: diagnosis, chemotherapy, radiotherapy, surgery and treatment completion. Patients with some histological types of neoplasms such as carcinomas, bone tumors and lymphomas are more prone to malnutrition. Difficulties in the ingestion and absorption of nutrients can occur due to psychological causes, pain, mucositis, vomiting, nausea, dysgeusia and dysosmia. A relevant aspect is that nutritional status of cancer patients affects the intensity of symptoms, disease prognosis and quality of life, in addition to influencing the pharmacokinetics and pharmacodynamics of drugs used in antineoplastic therapy, with deleterious consequences in terms of effectiveness and safety caused toxicity. However, early diagnosis of malnutrition favors the use of nutritional supplements whose experiences described in the literature demonstrate effectiveness in children and adolescents with cancer. Real knowledge of the incidence of malnutrition may allow early initiation of preventive and therapeutic measures with an influence on the prognosis and quality of life of this special group of children and adolescents.

Keywords : Malnutrition. Children. Adolescents. Malignant Neoplasms.