Nutritional support in multimodal therapy for cancer cachexia
Malnutrition has since long been known to be associated with adverse outcomes in cancer patients. The wasting in cancer cachexia involves loss of muscle and fat and reflects a catabolic metabolism induced by an abnormal host response to tumour presence and/or tumour factors. Patients with cancer cachexia frequently develop a chronic negative energy and protein balance driven by a combination of reduced food intake and metabolic change. Thus, alterations in both energy intake and components of energy expenditure may contribute to progressive weight loss. Increased resting energy expenditure related to the systemic inflammatory response is common and a sustained hypermetabolism over a long period of disease progression can make a large contribution to negative energy balance and wasting if not compensated for by an increase in energy intake. Hypermetabolism and diminished energy intake due to anorexia may thus constitute a vicious circle in the development of cancer cachexia.
Though nutritional support alone can improve energy intake to a variable extent and for a variable period of time, it will not address the underlying catabolic metabolism and is thus likely to be of limited efficacy if attempts to attenuate the tumour-induced catabolic response are not carried out at the same time. Concomitant drug treatments for cancer cachexia may slow down the wasting process by reducing anorexia, attenuating the systemic inflammation, the skeletal muscle catabolism or stimulating the muscle protein anabolism.
Thus, improved management of cancer cachexia may require a multimodal approach by a multi-disciplinary team and is best commenced earlier rather than later. Early start of therapy also facilitates the use of oral nutritional supplementation, which is preferable to parenteral nutrition in the majority of cases. Once a patient is severely wasted it may be neither practical nor ethical to intervene with anything else than supportive care.
An improvement in the condition of all patients with cachexia may not be possible, however, the goal must be to stabilise cachexia and prevent or delay further decline. There is currently no single or combined treatment strategy which is successful in all patients. However, strategies to counteract both hypermetabolism and reduced dietary intake have been demonstrated to be of importance for the survival, function and quality of life of cancer patients and should be further explored in interventional studies.