Résumé
More and more obese or overweight patients are being treated in oncology. Nutritional evaluation of these patients includes body mass index, weight and its evolution, and visual scale of ingesta. The study of-body composition seems promising but it is not carried out in common practice. The prognosis of obese or overweight patients is often better than for other patients, except in breast cancer or in case of associated sarcopenia. For the measurements of nutritional requirements, the weight should be calculated for a theoretical body mass index between 25 and 30 kg/m(2). In oncology, the adaptation of doses of chemotherapy is an outstanding question with risks of over- or under-dosage, requiring further studies. In the context of radiotherapy, technical difficulties may be encountered for some obese patients and more pronounced toxicities in case of breast irradiation if the volume of the breast is large. The recommendations for nutritional management are the same as for non-obese patients, particularly in head and neck or colorectal cancers. Early nutritional management is essential for patients with a BMI >25 kg/m(2), treated for breast cancer. In a palliative situation, if technical difficulties exist for patients with major obesity, there are no studies in this case. (C) 2017 Published by Elsevier Masson SAS on behalf of Association pour le developpement de la recherche en nutrition (ADREN).