NUTRITION

Optimizing nutrition for patients with cancer involves early detection of malnutrition or risk of malnutrition so that intervention may be initiated in the early stages of disease or treatment. The goal of nutrition screening is to rapidly identify patients who are at risk of developing malnutrition and refer them to a health care professional, ideally a registered dietitian, who can perform a complete nutrition assessment and implement a nutrition care plan.

There are no standard definitions or indices of malnutrition. Historically, loss of weight or body mass index (BMI), low BMI, and low serum protein (e.g., albumin) have been used to identify patients with malnutrition. Without more context, these characteristics are not acceptable measures by which to determine malnutrition. Weight changes alone cannot be used to determine nutrition status because weight changes do not account for fluid changes (dehydration, ascites, and edema) or disproportionate loss of lean body mass. Likewise, evidence demonstrates that BMI is deceiving because it does not account for body composition (lean body mass vs. fat mass), and many patients with cancer may present with a normal or high body weight/BMI but have severe muscle depletion (i.e., sarcopenia). The use of albumin, which is now recognized as being significantly influenced by inflammation, is also a poor measure of nutrition status and more likely suggestive of disease severity, not nutrition status. Standardized definitions and cutoff points that designate malnutrition or cachexia are being developed; however, the true prevalence of malnutrition in the oncology population is unknown.

A growing body of literature examines the prevalence of malnutrition in cancer patients with obesity. In a study of clinical data obtained from 1,469 patients with metastatic primary cancers, 41.9% were identified as overweight or obese. Upon assessment, 50% were at risk of being malnourished, and 12% were already malnourished at presentation. Malnutrition, even in the presence of obesity, has been found to be an independent predictor of survival, with patients presenting with sarcopenic obesity having the poorest prognosis. Therefore, these data suggest that the assessment of malnutrition among patients of every weight status is important.

Obesity has been shown to increase the risk of cancer recurrence, and it negatively impacts overall survival.

The prevalence of obesity is higher in adult cancer survivors than in those without a cancer history. Cancer survivors with the highest rates of increasing obesity are colorectal and breast cancer survivors and non-Hispanic Black individuals. Emerging evidence supports the efficacy of intentional weight loss in overweight or obese cancer patients and survivors to reduce the risk of recurrent disease and improve prognosis, particularly among breast cancer patients. Similar research is under way for patients with other obesity-related cancers.

Screening

Early recognition of nutrition-related issues is necessary for appropriate nutrition management of cancer patients. Nutrition screening can be performed with a validated tool before treatment begins and at regular intervals over the course of treatment.

In the outpatient oncology setting, it is recommended that patients be screened initially before treatment begins and rescreened at planned intervals. Screening can most often coincide with the patient’s treatment schedule, such as weekly during radiation therapy and as frequently as every 2 to 3 weeks during chemotherapy, before surgery, and at follow-up visits after completion of treatment or surgical recovery.

The following five screening tools are validated for use in oncology:

The Malnutrition Screening Tool for Cancer Patients.
The Malnutrition Universal Screening Tool.
The Malnutrition Screening Tool (MST).
The Patient-Generated Subjective Global Assessment (PG-SGA).
The NUTRISCORE tool.

Assessment

Nutrition assessment is a comprehensive approach to evaluating and diagnosing nutrition problems and designing interventions. A full nutrition assessment involves evaluation of the following six components:

Food- and nutrition-related history.
Anthropometric measurements.
Biochemical data, medical tests, and procedures.
Nutrition-focused physical assessment.
Medical history.
Treatment plan.

The assessment of anthropometric measurements evaluates weight loss, takes into account the time frame of weight loss, and is considered in the context of physical findings such as dehydration or fluid retention. Evaluation of food- and nutrition-related history ideally involves a dietitian obtaining a diet history and comparing intake with the patient’s calculated energy needs. The nutrition-focused physical assessment evaluates loss of muscle mass and subcutaneous fat, fluid accumulation, and potential micronutrient deficiencies.

Diets

Vegetarian or vegan diet

A vegetarian diet is popular, is easy to implement, and, if followed carefully, does not result in nutritional deficiencies. There is strong evidence that a vegetarian diet reduces the incidence of many types of cancer, especially cancers of the gastrointestinal (GI) tract. However, it is unknown how following a vegetarian or vegan diet can affect treatment-induced symptoms, cancer therapies, or outcomes for someone undergoing cancer therapy. There are no published clinical trials, pilot studies, or case reports on the effectiveness of a vegetarian diet for the management of cancer therapy and symptoms. There is no evidence suggesting a benefit of adopting a vegetarian or vegan diet upon diagnosis or while undergoing cancer therapy. On the other hand, there is no evidence that an individual who follows a vegetarian or vegan diet before cancer therapy should abandon it upon starting treatment.

The Men’s Eating and Living (MEAL) Study was a randomized trial of men with early-stage prostate cancer. It compared participants who were managed with active surveillance and behavioral counseling with a control group who received no counseling. The study found that the intervention to increase vegetable intake was successful—there was a statistically significant increase in consumption. However, time to cancer progression did not differ between the two groups.

Potential benefits of dietary isothiocyanates (ITC), a phytochemical, were observed in the Be-Well study. Results from 1,143 participants in this study who had non–muscle-invasive bladder cancer indicated some benefits from dietary ITC consumption through cruciferous vegetables. Levels of self-reported cruciferous vegetable consumption, estimated ITC intake levels (calculated from self-reported cruciferous vegetable consumption), ITC urine metabolites levels, and plasma ITC-albumin adducts levels were analyzed in association with disease progression. Compared with having one recurrence, participants with higher raw cruciferous vegetable consumption were less likely to have two or more recurrences (OR, 0.34; 95% CI, 0.16–0.68). Participants with higher levels of plasma ITC-albumin adducts had a lower risk of disease progression, and a lower risk of progression to muscle-invasive disease was observed in participants with higher benzyl ITC levels (HR, 0.40; 95% CI, 0.17–0.93) or higher phenethyl ITC levels (HR, 0.40; 95% CI, 0.19–0.86). Further research on benefits of phytochemicals is warranted.

Macrobiotic diet

A macrobiotic diet varies according to a person’s sex, their level of activity, and the climate (and season) where they live, among other variables. It is a high-carbohydrate, low-fat, plant-based diet stemming from philosophical principles promoting a healthy way of living. The diet consists of 35% to 50% (by weight) whole grains, 25% to 35% vegetables, 5% to 10% soup, 5% to 10% cooked vegetables and sea vegetables, and 5% to 10% fish.

Although there are anecdotal reports of the effectiveness of a macrobiotic diet as an alternative cancer therapy, none has been published in peer-reviewed, scientific journals. No clinical trials, observational studies, or pilot studies have examined the diet as a complementary or alternative therapy for cancer. In fact, two reviews of the diet concluded that there is no scientific evidence for the use of a macrobiotic diet in cancer treatment. Because the current research is severely lacking, recommendations for or against the diet in conjunction with standard cancer treatment cannot be made. No current clinical trials are studying the role of the macrobiotic diet in cancer therapy.

Ketogenic diet

A ketogenic diet has been well established as an effective alternative treatment for some cases of epilepsy and has gained popularity for use in conjunction with standard treatments for glioblastoma. The theory behind the diet as cancer treatment is that reducing glucose availability to a tumor can reduce tumor activity, and that this reduction can be achieved through entering a state of ketosis via the ketogenic diet’s increased fat intake and restriction of carbohydrates.

The ketogenic diet can be difficult to follow and relies more on exact proportions of macronutrients (typically a 4:1 ratio of fat to carbohydrates and protein) than other complementary and alternative medicine (CAM) diets.

Most studies have focused on the diet’s feasibility, tolerability, and safety, all of which have been shown for patients with glioblastoma at various stages of the disease. Because safety and feasibility have been proven, several trials are recruiting patients to study the effectiveness of the ketogenic diet on glioblastoma. Therefore, it is safe for a patient diagnosed with glioblastoma to start a ketogenic diet if implemented properly and under the guidance of a registered dietitian. However, effectiveness for symptom and disease management remains unknown.

Similarly, findings from a study that compared the acceptability and adverse effects of a ketogenic diet to the American Cancer Society's high-fiber, low-fat diet among women with ovarian or endometrial cancer found no differences between groups over 12 weeks. Further, the findings indicated that the ketogenic diet was both safe and acceptable. The effectiveness for symptom and disease management for ovarian or endometrial cancer also remains unknown.

Dietary Supplements

Vitamin C

For information about the use of intravenous vitamin C as a treatment for people with cancer, see Intravenous Vitamin C.

Probiotics

The use of probiotics has become prevalent within and outside of cancer therapy. Strong research has shown that probiotic supplementation during radiation therapy, chemotherapy, or both is well tolerated and can help prevent radiation- and chemotherapy-induced diarrhea, especially in those receiving radiation to the abdomen. If a patient is undergoing radiation to the abdomen or receiving a chemotherapy agent with diarrhea as a common side effect, starting a probiotic supplement upon initiation of therapy could be beneficial. Evidence is also emerging for possible benefits of probiotics for immunotherapy-induced toxicities, particularly in the colon.

Melatonin

Melatonin is a hormone produced endogenously that has been used as a CAM supplement (along with chemotherapy or radiation therapy) for targeting tumor activity and for reducing treatment-related symptoms, primarily for solid tumors.

Several studies have shown tumor response to, or disease control with, chemotherapy alongside oral melatonin, as opposed to chemotherapy alone. One study has shown tumor response with melatonin in conjunction with radiation therapy. The combination of melatonin and chemotherapy may, in fact, increase survival time by up to 5 years compared with chemotherapy alone. However, another study did not demonstrate increased survival with melatonin, but did demonstrate improved quality of life.

Melatonin taken in conjunction with chemotherapy may help reduce or prevent some treatment-related side effects and toxicities that can delay treatment, reduce doses, and negatively affect quality of life. Melatonin supplementation has been associated with significant reductions in neuropathy and neurotoxicity, myelosuppression, thrombocytopenia, cardiotoxicity, stomatitis, asthenia, and malaise. However, one study found no benefit in taking supplemental melatonin for reducing toxicities or improving quality of life.

Overall, several small studies show some evidence supporting melatonin supplementation alongside chemotherapy, radiation therapy, or both for solid tumor treatment, aiding tumor response, and reducing toxicities. Negative side effects for melatonin supplementation have not been found. Therefore, it may be appropriate to provide oral melatonin in conjunction with chemotherapy or radiation therapy to a patient with an advanced solid tumor.

Oral glutamine

Glutamine is an amino acid that is especially important for GI mucosal cells and their replication. Chemotherapy and radiation therapy often damage these cells, causing mucositis and diarrhea, which can lead to treatment delays and dose reductions and severely affect quality of life. Some evidence suggests that oral glutamine can reduce both of those toxicities by aiding in faster healing of the mucosal cells and entire GI tract.

For patients receiving chemotherapy who are at high risk of developing mucositis, either because of previous mucositis or having received known mucositis-causing chemotherapy, oral glutamine may reduce the severity and incidence of mucositis.

For patients receiving radiation therapy to the abdomen, oral glutamine may reduce the severity of diarrhea and can lead to fewer treatment delays. However, one study found no benefit to oral glutamine for preventing chemotherapy-related diarrhea.

In addition to reducing GI toxicities, oral glutamine may also reduce peripheral neuropathy in patients receiving the chemotherapy agent paclitaxel. Larger randomized controlled trials are needed to further determine the effectiveness of oral glutamine in treating peripheral neuropathy.

Oral glutamine is a safe, simple, and relatively low-cost supplement that may reduce severe chemotherapy- and radiation-induced toxicities.