The Importance of Nutrition During Cancer Treatment
The nutritional status of cancer patients is often compromised as a symptom of the cancer or as a side effect of conventional treatment (Usharani K et al 2004). Indeed, a significant number of patients recovering from cancer are malnourished (Guo Y et al 2005) or have suffered considerable weight loss (Colasanto JM et al 2005). The nutritional status of cancer patients has an impact on a variety of important factors, including:
Nutritional intervention as an integral part of cancer treatment can be implemented by eating healthy foods and taking supplements or by administration of enriched formulas through a feeding tube directly into the gastrointestinal tract (enteral) or injection into the veins (parenteral) (Hyltander A et al 2005). Enteral nutrition is always the preferred method of feeding cancer patients when the gastrointestinal tract is functional but the oral route is compromised; parenteral nutrition should be provided only to selected patients, as it is of little benefit to most cancer patients.
However, parenteral nutrition can be administered in the comfort of the patient’s home and improves the long-term survival of patients with incurable advanced disease (Hoda D et al 2005). In particular, this type of artificial feeding can be useful in gynecological and colon cancer patients who often suffer from intestinal tract obstruction (McKinlay AW 2004). In a recent study comparing the different types of nutritional intervention during cancer treatment, normal oral nutrition was superior to enteral and parenteral feeding only when it was supported by nutritional counseling from a dietician (Hyltander A et al 2005).
Treatment Tolerance. Nutritional intervention during cancer treatment may help patients to better tolerate cancer treatment, with less frequent adverse side effects (Bahl M et al 2004; Capra S et al 2001; Read JA et al 2004). In particular, patients with nasopharyngeal cancer, when artificially fed through a tube before treatment, had less weight loss and superior recovery compared to patients who had the nutritional intervention only after treatment (Bahl M et al 2004).
Survival and Overall Outcome. Malnourished cancer patients are more likely to have longer periods of hospitalization, lower survival rates, and a higher frequency of medical complications (Colasanto JM et al 2005; Guo Y et al 2005). A study of stomach cancer patients recently showed that nutritional status affected the patients’ quality of life, and the authors recommended increasing the number of high-protein, high-calorie meals consumed each day as a way to improve nutritional status (Tian J et al 2005).
Studies of colorectal and head and neck cancer patients have shown the beneficial effect of nutrition on survival and quality of life (Ravasco P et al 2005b; Ravasco P et al 2005a). These studies have also highlighted the importance of cancer patients having access to counseling and guidance from a dietician. In fact, these studies showed that regular foods supported by dietary counseling were more beneficial than enriched nutritional supplements taken in the absence of qualified guidance (Ravasco P et al 2005b; Ravasco P et al 2005a).
Immune Function. Impaired nutritional status in cancer patients is associated with reduced numbers of white blood cells (most often neutropenia) and low red blood cell counts, or anemia (Usharani K et al 2004). Administration of a specialized formula enriched with nutrients (including arginine and omega-3 fatty acids) to cancer patients before surgery reduced the occurrence of infections and time spent in the hospital (Moskovitz DN et al 2004). Because of its immunomodulatory properties, arginine helps to restore immune system balance in cancer patients after surgery (Ates E et al 2004); however, further research is necessary to define its role in the nutritional care of cancer patients
Delays in the healing of surgical wounds—or a complete failure of the wounds to heal—often complicates the rehabilitation of malnourished cancer patients after surgery (Farreras N et al 2005). Artificial nutrition of gastric cancer patients after surgery with a formula designed to boost the immune system improves wound healing and recovery (Farreras N et al 2005).
Cancer Development and Progression
. A study of patients with high levels of prostate-specific antigen (PSA), a widely accepted indicator of the risk of developing prostate cancer, showed that a diet of low fat and high soybean protein content induced a significant, though temporary, reduction in PSA levels (Tsutsumi M et al 2004).