Medical Nutrition Therapy (MNT) Guidelines for Cancer in Adults

1. Introduction

Cancer and its treatment profoundly affect nutritional status. Malnutrition, weight loss, and altered body composition are common and can worsen treatment tolerance, quality of life, and survival. Medical Nutrition Therapy (MNT) is a systematic, evidencebased approach that aims to meet the unique metabolic, energy, and protein needs of adults with cancer while managing symptoms that interfere with oral intake.

2. Core Principles of MNT for Cancer

2.1 Individualized Assessment

Nutrition assessment should be performed by a registered dietitian (RD) using a comprehensive tool such as the PatientGenerated Subjective Global Assessment (PGSGA) or the Academy of Nutrition and Dietetics Nutrition Care Process. Key elements include:

• Weight history (current weight, recent loss/gain, BMI)
• Dietary intake (24hour recall, food frequency)
• Biochemical data (albumin, prealbumin, CRP)
• Physical exam (muscle wasting, edema)
• Symptoms affecting intake (nausea, dysgeusia, mucositis, xerostomia)
• Treatment plan (type of surgery, chemotherapy, radiation, immunotherapy)

2.2 Energy and Protein Requirements

Energy needs are typically 2530kcal/kgbodyweight per day for sedentary patients, but can increase to 3035kcal/kg for those with fever, infection, or highintensity therapy. Protein requirements rise to 1.21.5g/kgbodyweight per day, and up to 2.0g/kg for patients with severe catabolism or wound healing needs.

2.3 Micronutrient Considerations

Routine highdose supplementation is not recommended unless a specific deficiency is documented. However, the following are often considered:

• Vitamin D (8001,000IU/day) for bone health
• Iron, folate, or B12 when labs indicate deficiency
• Omega3 fatty acids (24g EPA/DHA per day) for cachexia and inflammation

2.4 SymptomTargeted Nutrition

Addressing symptoms is central to MNT. Strategies include:

• Nausea/vomiting: Small, frequent meals; bland, lowfat foods; ginger or antiemetics before meals.
• Mucositis: Soft, nonabrasive foods; avoiding acidic or spicy items; use of nutritional supplements with a neutral pH.
• Altered taste/smell: Use of herbs, marinades, or flavor enhancers; serving foods at cooler temperatures.
• Diarrhea: Lowfiber, lowfat diet; adequate hydration; consider probiotics if appropriate.
• Constipation: Highfiber foods, increased fluids, regular physical activity.

3. Nutritional Interventions

3.1 Oral Nutrition Support (ONS)

Firstline therapy for most patients. Choose highcalorie, highprotein formulas (1.52.0kcal/mL; 20g protein per 250mL). Offer 12 servings per day, adjusting volume based on tolerance.

3.2 Enteral Nutrition (EN)

Indicated when oral intake is <60% of estimated needs for >7days and the gastrointestinal tract is functional.

• Placement: nasogastric tube for shortterm (<4weeks) or percutaneous endoscopic gastrostomy (PEG) for longer durations.
• Formula selection: diseasespecific (e.g., peptidebased for malabsorption) or standard polymeric formulas.
• Goal rate: start at 20mL/h and advance as tolerated to meet 100% of calculated needs.

3.3 Parenteral Nutrition (PN)

Reserved for patients with nonfunctional GI tract or severe malabsorption where EN is not feasible. PN should be individualized, providing 2030kcal/kgday and 1.52.0g protein/kgday, with careful monitoring of electrolytes, glucose, and hepatic function.

3.4 Supplemental Strategies

• Probiotic and prebiotic use: May improve gut microbiota and reduce diarrhea, but should be used cautiously in immunocompromised patients.
• Appetite stimulants: Megestrol acetate (400800mg/day) or corticosteroids for short periods when appetite is severely reduced.
• Exercise: Light resistance training combined with nutrition improves muscle mass and functional status.

4. Monitoring and Reevaluation

Nutrition status must be reviewed at least every 2weeks during active treatment and monthly during survivorship or palliative phases.

• Weight and BMI
• Dietary intake records
• Laboratory markers (CRP, albumin, prealbumin, electrolytes)
• Symptom logs (pain, nausea, taste changes)
• Adjust energy/protein targets based on changes in metabolism or treatment phase.

5. Special Situations

5.1 Head & Neck Cancer

High incidence of dysphagia and mucositis. Early referral for speechlanguage pathology and consideration of prophylactic PEG placement in patients expected to have >10days of nilbymouth status.

5.2 Gastrointestinal Cancers

Risk of malabsorption and short bowel syndrome. Use elemental or semielemental formulas; monitor fatsoluble vitamins and trace elements.

5.3 Hematologic Malignancies

Chemotherapyinduced neutropenia may limit use of highrisk probiotics. Emphasize food safety (pasteurised, wellcooked foods) and consider neutropenic diet guidelines.

5.4 Palliative Care

Goal shifts to comfort and quality of life. Small, nutrientdense meals, favorite foods, and limited use of aggressive nutritional support are appropriate.

6. Practical Tips for Caregivers and Patients

• Keep a food and symptom diary to identify trigger foods.
• Offer 56 small meals/snacks rather than three large meals.
• Use caloriedense addins: nut butters, avocado, olive oil, or powdered supplements blended into smoothies.
• Stay hydrated but avoid large volumes of fluid with meals if early satiety is an issue.
• Plan meals around treatment schedules; eat when appetite is highest (often midmorning or early evening).
• Educate on safe food handling, especially for immunocompromised patients.

7. Summary

Medical Nutrition Therapy for adult cancer patients is a dynamic, patientcentered process that integrates thorough assessment, individualized energy and protein targets, symptomdirected interventions, and regular reevaluation. Early involvement of a registered dietitian, combined with coordinated care among oncology, nursing, and supportive services, maximizes nutritional status, supports treatment tolerance, and improves overall outcomes.

For detailed protocols, clinicians are encouraged to consult the latest American Society for Clinical Oncology (ASCO) nutrition guidelines, the European Society for Clinical Nutrition and Metabolism (ESPEN) consensus statements, and institutionspecific pathways.