Specialty nutrition for patients with cancer is an exciting area in research. It is well known that patients with cancer experience many nutritional problems during the course of their disease-in particular anorexia and weight loss.[1,2] Specialty nutrition can impact nutritional status directly by improving weight and lean body mass, or indirectly by improving common symptoms often associated with cancer and cancer therapies.
Weight loss among patients with cancer negatively impacts outcomes such as[3,4] response to therapy and overall rate of survival and quality of life. In fact, weight loss is reported to be an independent predictor of prognosis and survival, and improved survival has been observed in patients achieving weight stabilization. Therefore, many research efforts have focused on the effects of specialty nutrition on weight loss.
Common strategies for improving weight and nutritional status in patients with cancer have included nutritional counseling, nutritional supplementation,[ 6] and appetite stimulants such as megestrol(Drug information on megestrol) acetate (Megace) or dronabinol (Marinol). Studies have shown that these strategies help improve appetite and caloric intake but do not result in improved weight or lean body mass because they do not address underlying alterations in metabolism. Weight loss can be attributed to mechanical reasons (ie, tumor obstruction of the gastrointestinal tract), treatmentrelated effects, or tumor-related effects. In tumorinduced weight loss it is difficult to improve weight status without addressing the underlying metabolic problems of anorexia, elevated resting energy expenditure, and altered macronutrient metabolism.
Supplementation with fish oil or eicosapentaenoic acid (EPA) has been shown to stabilize weight in phase II trials in weight-losing patients with pancreatic cancer by downregulating the proinflammatory response thought to be responsible for metabolic alterations.[7,8] Studies of an energy- and proteindense EPA-containing supplement have resulted in improvements in weight, lean body mass, quality of life, and increased activity level in weight-losing patients with pancreatic cancer.[9,10] Eicosapentaenoic acid is thought to address the underlying metabolic problems by downregulating the inflammatory response while the calories and protein provide substrates for increased weight and lean body mass.
Specialty nutrition can also indirectly affect nutritional status by ameliorating common symptoms such as nausea, constipation, mucositis, and fatigue. Studies are ongoing to find ingredients to help alleviate the nausea that often accompanies cancer therapies. While there are many effective pharmacologic treatments for vomiting, nausea often persists and impedes appropriate dietary intake. Hydration can also relieve cancer-related symptoms such as constipation, mucositis, and dry oral mucosa, which can further aggravate mucositis and delay return of oral intake. Adequate hydration status may reduce pain and the need for pain medication and toxicity of some chemotherapeutic agents to the kidney, brain, or liver. Novel agents may improve absorption of fluids. Nutritional products containing fiber such as fructooligosaccharides (FOS) may also be effective in combating constipation. Recent studies on the effect of carnitine on chronic fatigue may lead to nutritional interventions for the cancer patients.
Important considerations in the research of novel ingredients include potential side effects, effect on tumor growth, quality of life, and survival. Categorizing patients according to their primary cause of weight loss (ie, mechanical vs treatment related vs tumor related) is essential to effectively evaluate the outcomes of the intervention. Lastly, it is important to assure that the outcomes evaluated in a study are clinically relevant to both the clinician and the patient.