Nutritional status in cancer.

A decline in nutritional status is seen in many, but not all cancer patients. The factors leading to this decline are complex and include anorexia, malabsorption and alterations in energy expenditure. The end result of this decline is cachexia, but it is questionable whether this syndrome differs materially from that seen in severe undernutrition arising from other causes. Of the measurable changes in body composition taking place in cancer patients those of most importance are losses of lean tissue, which result in a reduced functional capacity for organ systems. Such losses are difficult to detect because accumulated water may mask many of the early changes in composition and make conventional assessment of nutritional status unreliable. Nutritional support should be provided for undernourished patients, irrespective of the primary cause of their poor nutrition, but there is no convincing evidence that the treatment of nutritional deficiencies alone improves the outcome in cancer patients.