There are no standard evidence-based recommendations for diet therapy during cancer treatment, due in part to the heterogeneous nature of this disease. Loss of appetite and severe weight loss (cachexia) are common in many cancer patients, and significant weight loss at the time of diagnosis—as well as malnutrition that may occur during the course of the disease—is a predictor of poor outcome. Malnutrition also impairs the response to chemotherapy. Due to these risks, the National Cancer Institute (NCI) suggests early nutrition screening and intervention, as well as close monitoring and evaluation of patients throughout all phases of cancer treatment and recovery.
The goals of nutrition assessment and therapy should include opposing the effects of hormones and growth factors on angiogenesis and metastasis, as well as inhibiting proliferation of cancer cells; prevention or reversal of nutrient deficiencies; preservation of lean body mass; increased tolerance for anticancer treatments with a minimization of nutrition-related side effects and complications; decreased risk for infection through support of immune function; facilitation of recovery and healing; and maintenance of strength, energy, and quality of life. Diet can also be used to help control blood pressure in patients receiving cancer treatment. The incidence of hypertension increases with chemotherapy and encourages the development of cardiomyopathy.
NCI recommends 2 methods of assessing nutritional status in cancer patients:
Additional criteria suggesting a need for oral, enteral, or parenteral nutrition support include:
Weight loss caused by the disease process should be differentiated from healthful weight loss in overweight individuals. In certain cancers (e.g., breast, colon, and prostate), higher body weight, greater percent body fat, and excess weight gain during treatment have been associated with increased mortality after diagnosis. One study of 526 individuals with colon cancer found that every 10% increase in body fat was associated with a 33% decrease in cancer survival. Caution should therefore be exercised in trying to prevent weight loss in individuals for whom such loss would otherwise be therapeutic, particularly in light of findings that adipocytes secrete adipocytokines (e.g., leptin) that have an agonistic effect on cancer growth.
Conversely, in individuals with abnormal weight loss, identification of nutrition problems and treatment of nutrition-related symptoms have been shown to stabilize or reverse weight loss in 50% to 88% of oncology patients. These clinical efforts frequently focus on increasing food intake by any means acceptable to patients; however, as is the case with protein-calorie supplements, evidence indicates mortality does not improve. There is evidence suggesting that ad libitum diets high in animal protein and other macronutrients that raise insulin and IGF-1 levels (e.g., refined carbohydrates) maintain a malignant state, through the downstream effects of mechanistic target of rapamycin, a member of the phosphatidylinositol 3-kinase-related kinase protein family that regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, autophagy, and transcription. These in turn lead to immune suppression and inflammation, foster cell proliferation and metastasis, interfere with effective treatment, and potentially worsen survival.
Nutrition therapy should be individualized. In colorectal cancer patients, providing patients with diet therapy based on an analysis of macro- and micronutrients missing or present in excess resulted in significant improvements in mortality, survival time, and quality of life, when compared with patients given either no form of nutrition support or dietary supplements alone. Similarly, a systematic review of individualized nutrition counseling in head and neck cancer patients found better weight maintenance and smaller numbers of patients with malnutrition, when compared with control groups receiving standard (i.e., nonindividualized) nutrition advice or no advice.
Nutrition therapy should emphasize a plant-based diet and avoidance of a Western dietary pattern. The role of Western diets as a contributing factor in cancer incidence is well-established. These diets contain carcinogens and influence circulating hormone concentrations, while often being low in compounds associated with cancer protection.
Nutrition also influences cancer survival. In men with prostate cancer, those whose diets most closely followed a Western diet had more than two and one-half times the risk for prostate cancer-specific mortality, compared with those who diets were least Western in nature. Similarly, when compared with the lowest intake of red meat, individuals consuming red meat more often after diagnosis of either colorectal cancer or cutaneous melanomas > 1 mm thick had a significantly greater risk for cancer-specific mortality. In overweight or obese patients with stage III colon cancer, diets higher in glycemic load (GL) were significantly associated with poorer disease-free survival when compared with those whose diets were the lowest GL. Similarly, these same patients (along with those who were less physically active) who consumed sugar-sweetened beverages twice per day had a significantly greater cancer-specific mortality risk when compared with patients who consumed these twice per month or less. By comparison, diets that have higher amounts of anti-inflammatory foods showed a linear association with survival time in patients with non-metastatic, surgically treated colorectal cancer patients, when compared with those eating the fewest anti-inflammatory foods.
Plant-based diets provide higher amounts of isoflavones from soy protein and carotenoids from fruits and vegetables. Both of these provide a significant survival advantage for women who have been diagnosed with breast cancer, when compared with those eating the lowest amount.
Current nonspecific nutrition recommendations for patients with cancer provided by the NCI are described below.
Gastrointestinal disturbances. For diarrhea, NCI recommendations include consuming foods high in sodium and potassium (e.g., broth, sports drinks, and bananas, peach and apricot nectar, and boiled or mashed potatoes) and bland, low-fiber foods (e.g., rice, noodles, farina or cream of wheat, smooth peanut butter, white bread, canned, peeled fruits, and well-cooked vegetables), as well as avoiding very hot, cold, or caffeinated foods or beverages.
Recommendations for constipation include a high-fiber diet (with physician approval, due to potentially undesirable effects in certain individuals), along with maintenance of physical activity and consumption of a warm drink about half an hour before the usual time for a bowel movement, in the context of a high total fluid volume (at least 64 ounces per day).
Patients undergoing colonic resection often experience negative changes in intestinal microbial balance, deterioration of gut barrier function, systemic inflammation and reduced immune function that result in postoperative infections. Meta-analyses of the effects of probiotic and symbiotic formulations have found that these protect the intestinal mucosa barrier, decrease infection morbidity, and reduce the incidence of diarrhea and other problematic gastrointestinal symptoms in these patients.
The National Cancer Institute, the National Comprehensive Cancer Network (a nonprofit alliance of 20 cancer care centers throughout the United States), and the American Cancer Society suggest the following dietary strategies to control the nausea and vomiting associated with chemotherapy:
If these suggestions do not prevent vomiting, a clear liquid diet is suggested, with progression to a full liquid diet and then a soft diet (i.e., bland foods that are softened by cooking, mashing, puréeing, or blending) as tolerated. These suggestions are anecdotal in nature and have not been tested in controlled clinical trials.
Certain botanical treatments (e.g., ginger) have been found effective for controlling chemotherapy-induced nausea and vomiting. Ginger extracts, although controversial (due in part to the chemical instability of easily oxidized active compounds) impart antinausea/antiemetic actions through effects on cholinergic M receptors as well as 5-HT and 5-HT receptors. The effects of ginger have been found equal to those of metoclopramide, and a randomized, double-blind, placebo-controlled clinical trial conducted in 23 private practice oncology groups found that when combined with standard 5-HT receptor antagonists, ginger significantly reduced nausea when compared with placebo treatment.
In addition to these suggestions, the National Comprehensive Cancer Network and the American Cancer Society suggest behavioral strategies for the “anticipatory” type of nausea and vomiting that occur as a conditioned response to many cancer therapies. These include self-hypnosis, progressive muscle relaxation, biofeedback, guided imagery, and systematic desensitization.
Anorexia and cachexia. Cancer-induced cachexia and the proteolysis of lean tissue that occurs in many cancers is known to be caused by proinflammatory cytokines, including TNF- α and IL-6. In a study of head and neck cancer patients with an elevated proinflammatory cytokine profile, only those diets that emphasized healthier food choices were significantly associated with lower cytokine levels, when compared with individuals eating a Western foods or convenience foods pattern.
Suggestions provided by the NCI for this condition are not geared toward its root causes but instead relate to strategies that may prevent its sequelae. These include planning menus in advance; eating frequent meals and snacks that are easy to prepare; adding liquid calorie sources (e.g., juices, soups, milkshakes, and fruit smoothies); eating small, frequent (every 2 hours), high-calorie meals; snacking between meals; seeking foods that appeal to the sense of smell; and experimenting with different foods. Deficiency of L-carnitine is often induced by chemotherapeutic drugs and contributes to anorexia. In patients with advanced pancreatic cancer enrolled in a multi-center, placebo-controlled, randomized and double-blind trial and given oral L-carnitine (4 g) or placebo for 12 weeks, body mass index (BMI) increased significantly with carnitine treatment and decreased in the control group.
Radiation enteritis. Symptoms of radiation enteritis include nausea, vomiting, abdominal cramping, tenesmus, and watery diarrhea. According to the National Cancer Institute, a diet that is lactose-free, low in fat, and low in residue can be effective in symptom management. However, evidence supporting this approach is minimal and requires confirmation in controlled trials. Several controlled clinical trials in patients given pelvic radiotherapy found that probiotic formulations significantly reduced diarrhea and need for antidiarrheal medications. In selenium-deficient patients with gynecological cancers, a multicenter clinical trial found that sodium selenite supplements (500 μg/day during radiotherapy and 300 μg/day on days without) resulted in significant reductions in the rate of radiogenic diarrhea when compared to controls.
Chemotherapy-related mucositis and stomatitis. Chemotherapeutic agents known to induce vitamin D deficiency are known causes of mucositis and other side effects (see below) and may be successfully treated with vitamin D supplements. Oral cooling with ice chips for 30 minutes before bolus administration of chemotherapy (e.g., 5-FU) prevented mucositis and reduced symptoms by roughly half compared with a control group in one study. Practical dietary suggestions for dealing with this symptom include consuming foods cold or at room temperature rather than warm or hot, and eating soft foods that are easy to chew and swallow, while avoiding foods that are coarse in texture, difficult to chew (e.g., crackers, granola, toast, raw vegetables), or irritating (e.g., salty or spicy foods and citrus products). In patients treated with chemotherapy for a variety of cancers, oral glutamine (2 g/m delivered in a swish-and-swallow form or up to 4 g/d orally) decreased the severity and duration of oropharyngeal mucositis in addition to significantly reducing pain and the need for IV narcotics and parenteral nutrition in two studies. ,
A review of the effects of glutamine supplementation in cancer patients found that this amino acid reduces the effects of irinotecan and 5-FU on mucositis and stomatitis, protects against radiation-induced mucositis, anthracycline-induced cardiotoxicity and paclitaxel-related myalgias/arthralgias, and may prevent the neurotoxic effects of several different forms of chemotherapeutic agents. Previous studies found that glutamine supplementation decreased the incidence and severity of diarrhea, neuropathy, cardiotoxicity, and hepatic veno-occlusive disease that accompany the use of many chemotherapeutic agents.
Hypogeusia. Blunted taste sensation often occurs in patients undergoing chemotherapy and radiation. It occurs in up to 70% of chemotherapy-treated patients and may contribute to lack of appetite and poor dietary intake, which, in turn, can worsen a patient’s health status.
Vitamin D deficiency may also be responsible, and is caused in part by certain cytostatic chemotherapy drugs (e.g., cyclophosphamide, paclitaxel) that increase the enzymatic degradation of 25(OH)D and 1α,25(OH)2D. A related compound (docetaxel) is also known to cause taste disorders that were successfully treated with vitamin D supplementation. A controlled study in head and neck cancer patients found that high dose zinc (50 mg t.i.d.) was of significant benefit for this condition when compared with placebo; however, a Cochrane review concluded that the evidence for an effect of zinc treatment on taste disorders was of moderate quality and pertained only to those individuals with zinc deficiency.
Prevention of foodborne illness due to neutropenia. Although avoidance of all possible sources of microbial contamination has been suggested, a Cochrane review found no benefit from such an approach in patients rendered neutropenic by chemotherapy.
In addition to the above considerations, some evidence supports the use of the following interventions:
Coffee or green tea. Stage III colon cancer patients who consumed 4 or more cups per day of caffeinated coffee experienced a greater than 50% decrease in cancer recurrence and cancer mortality when compared with abstainers. These results have been attributed to the insulin-sensitizing, anti-inflammatory, antioxidant, antiangiogenic, antimetastatic, and proapoptotic effects of caffeine and other compounds found in coffee. In breast cancer patients supplemented with a green tea polyphenol (epigallocatchin-3-gallate, EGCG) during radiotherapy, significantly lower levels of biomarkers for angiogenesis (vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), metalloproteinase-9 and metalloproteinase-2) were found, along with a near-global suppression of cancer growth in cultured sera from these patients.
Dietary supplements. A systematic review of studies including mainly patients who had advanced or relapsed cancers concluded that (with the exception of vitamin A) the effectiveness of chemotherapy was increased by treatment with antioxidant supplements. Patients taking antioxidants had more full doses of chemotherapy or had less-dose reduction than control groups, and experienced an often statistically significant treatment response and/or survival time. Even taking a multiple vitamin-mineral supplement was found to lower mortality by 26% and prolong survival from 2 years to 4.3 years in a Mayo Clinic study of patients with lung cancer, compared with those not taking this type of supplement.
Eating foods high in omega-3 fats or taking omega-3 fatty acid supplements can also be helpful for cancer patients, in part by reducing inflammation and cachexia. A multicenter controlled trial found that lung cancer patients supplemented with fish oil gained weight and experienced progressive decreases in C-reactive protein and IL-6 when compared with patients given placebo. A study in breast cancer patients found that those with higher intake of marine fats had a 25% lower risk for additional breast cancer events when compared to those consuming the least.
Selenium supplementation can be helpful for patients with poor selenium status. In head and neck cancer patients, high dose selenium (500 μg/day during radiotherapy and 300 μg/day on days without) resulted in a statistically significant decrease in dysphagia when compared with controls. In women receiving chemotherapy for ovarian cancer, selenium supplementation (200 μg/d) significantly increased white blood cell count and decreased hair loss, abdominal pain, weakness, malaise, and loss of appetite. Short-term treatment with high doses of selenium (4000 μg/d) reduced nephrotoxicity and bone marrow suppression in cisplatin-treated patients. Further clinical trials are needed to establish the benefit and lack of toxicity of selenium doses in excess of Dietary Reference Intakes.
Specialized enteral formulas. A systematic review of studies concluded that an arginine-enriched formula significantly reduced the number of fistulas and hospital stay in patients undergoing surgery for head and neck cancer. Previous studies found that patients who received surgical treatment for gastric or head and neck cancers and were fed formulas containing arginine, glutamine, omega-3 fatty acids, RNA, or a combination of these demonstrated higher levels of total and T lymphocytes, T helper, and natural killer cells and a significant reduction in postoperative infections and wound complications. Apart from these effects, little evidence exists that specialized enteral formulas are superior to standard varieties for support of malnourished or surgical cancer patients.
Behavioral interventions. Published studies support the effectiveness of behavioral interventions for chemotherapy-related nausea and vomiting, including hypnosis, guided imagery, relaxation, and distraction.
Studies suggest that diet changes may reduce the likelihood of recurrence or other poor outcomes for certain types of malignancy. See Breast Cancer, Prostate Cancer, and Ovarian Cancer chapters for additional information.
Nutrition consultation: a dietitian should counsel the patient and family on meeting the patient’s energy needs and make recommendations regarding protein-calorie supplements.
Patients with cancer are often undernourished and malnourished. These problems may contribute to impaired treatment outcomes and increased morbidity. However, a more enlightened nutritional approach to diet than encouraging patients to eat ad libitum is needed both during and after cancer therapy. The family can help the patient make the necessary diet changes.