Cancer is a major cause of morbidity and mortality throughout the world. It is the second most frequent cause of death in Europe and is becoming the leading cause of death in old age. Patients with cancer will develop a large number of physical symptoms. Malnutrition and weight loss are common and are due to a variety of mechanisms involving the tumour, the host response to the tumour, and anticancer therapies. Inadequate intake of energy and nutrients alone is unable to account for the substantial changes in nutritional status seen in patients with cancer. In advanced cancer, cachexia often occurs. This complex multifactorial syndrome is associated with metabolic abnormalities, anorexia, early satiety and reduced food intake, depletion of lean body mass, muscle weakness, oedema, fatigue, impaired immune function, and declines in attention span and concentration. The development and implementation of screening and assessment tools is essential for effective nutritional intervention and management of patients with cancer. Proactive nutritional interventions should ideally form an integral part of cancer therapy, with the aim of improving clinical outcomes and quality of life. This supplement brings together a collection of papers discussing various topics regarding nutrition in cancer.