The Management of Neuroendocrine Tumours: A Nutritional Viewpoint

Neuroendocrine tumours (NETs) arise from hormonesecreting cells of the diffuse neuroendocrine system and can occur in the gastrointestinal tract, pancreas, lungs and other sites. Because many NETs produce bioactive substances, patients often experience complex metabolic disturbances that can be modified by diet and nutrition. This page summarises the key nutritional considerations that should be integrated into the multidisciplinary management of NETs.

1. Why Nutrition Matters in NETs

• Hormonerelated symptoms: carcinoid syndrome, diarrhea, flushing, hypoglycaemia, and gastric acid hypersecretion.
• Malabsorption: especially in smallintestinal NETs or after extensive bowel resection.
• Sarcopenia and cachexia: increased catabolism can reduce treatment tolerance.
• Treatmentrelated side effects: chemotherapy, peptidereceptor radionuclide therapy (PRRT), and targeted agents often cause nausea, vomiting, or taste changes.

2. Core Nutritional Goals

1. Maintain or restore body weight and lean muscle mass.
2. Control hormoneinduced diarrhoea and flushing.
3. Prevent micronutrient deficiencies.
4. Support immune function and wound healing.
5. Improve quality of life and treatment compliance.

3. Assessment Strategies

Before any dietary plan is introduced, a comprehensive assessment should be performed:

• Anthropometry weight, BMI, midupper arm circumference.
• Body composition bioimpedance or DEXA if available.
• Dietary recall 24hour or 3day food diary.
• Laboratory tests albumin, prealbumin, vitamin D, B12, iron, folate, electrolytes.
• Symptom inventory frequency of diarrhoea, flushing, abdominal pain, nausea.

4. Managing Specific Symptoms

4.1 Diarrhoea

Frequent, watery stools are common in functional NETs (e.g., carcinoid syndrome). Strategies include:

• Small, frequent meals 56 portions per day.
• Lowfat, lowsugar diet fats and simple sugars can worsen motility.
• Soluble fiber (e.g., oat bran, psyllium) to thicken stools; avoid insoluble fiber which may increase bulk.
• Stay hydrated with oral rehydration solutions; add oral electrolyte tablets if needed.
• Consider a lowhistamine diet if flushing persists.

4.2 Flushing

Triggers often include alcohol, hot beverages, spicy foods, and foods rich in tyramine. Patients should:

• Limit red wine, beer, spirits, and caffeine.
• Avoid aged cheeses, cured meats, and fermented soy products.
• Record personal triggers in a symptom diary.

4.3 Hypoglycaemia (Insulinoma)

For insulinproducing NETs, maintain stable glucose:

• Eat complex carbohydrates with each meal (whole grain breads, legumes, vegetables).
• Include protein and healthy fat to slow absorption.
• Snack every 23hours; keep quickacting glucose (e.g., glucose tablets) on hand.

4.4 Gastric Acid Hypersecretion (ZollingerEllison syndrome)

High acid can cause ulceration and malabsorption of nutrients such as iron and calcium.

• Separate acidic foods (citrus, tomato) from ironrich meals.
• Take a calcium citrate supplement with meals.
• Consider a lowacid diet and discuss protonpump inhibitor use with the medical team.

5. General Dietary Recommendations

• Protein: 1.21.5g/kg body weight daily to preserve muscle. Good sources lean poultry, fish, eggs, lowfat dairy, legumes.
• Healthy fats: Emphasise mono and polyunsaturated fats (olive oil, avocado, nuts). Limit saturated fats to <10% of total calories.
• Complex carbohydrates: Whole grains, starchy vegetables, fruit (moderate portions if diarrhea is an issue).
• Fiber: 2030g/day of mostly soluble fiber; increase gradually to avoid bloating.
• Fluids: Minimum 2L/day, more if diarrhoea is present.
• Micronutrients: Monitor vitamin D, calcium, B12 and iron. Supplement when laboratory values indicate deficiency.

6. Nutrition During Specific Treatments

6.1 Chemotherapy & Targeted Agents

These therapies can cause nausea, mucositis and taste changes. Recommendations:

• Plain, bland foods (e.g., plain rice, boiled potatoes, toast).
• Proteinrich smoothies with whey or pea protein.
• Ginger tea or peppermint for nausea.
• Small, frequent meals and avoid largevolume meals.

6.2 PeptideReceptor Radionuclide Therapy (PRRT)

Renal protection is vital. Encourage adequate hydration (2L/day) and a lowsodium diet to reduce renal load.

6.3 Somatostatin Analogues (Octreotide, Lanreotide)

These drugs can delay gastric emptying and reduce bile secretion, leading to steatorrhea.

• Consider mediumchain triglyceride (MCT) oil as an easily absorbed fat source.
• Enzyme replacement (pancrelipase) may be needed if fat malabsorption is documented.

7. Role of the Dietitian

A qualified dietitian experienced in oncology should be part of the care team. Their responsibilities include:

• Developing individualized meal plans.
• Monitoring weight, body composition and laboratory markers.
• Educating patients on symptomtrigger foods.
• Adjusting nutrition support (oral supplements, enteral feeding) when oral intake is insufficient.

8. When Oral Nutrition Is Not Enough

In advanced disease or after major surgery, patients may need supplemental nutrition:

• Oral nutritional supplements (ONS): highprotein, highcalorie formulas given between meals.
• Enteral feeding: nasogastric or percutaneous endoscopic gastrostomy (PEG) if the gastrointestinal tract is functional.
• Parenteral nutrition: reserved for cases where the gut cannot be used.

9. Lifestyle Adjuncts

• Lighttomoderate aerobic activity (walking, cycling) 150min/week, as tolerated, to preserve muscle mass.
• Stressreduction techniques (mindfulness, yoga) may lower flushing episodes.
• Smoking cessation and limiting alcohol intake improve overall outcomes.

10. Key TakeHome Messages

1. Nutrition is a cornerstone of NET management, influencing symptoms, treatment tolerance and survival.
2. Regular assessment and early intervention prevent malnutrition and sarcopenia.
3. Tailor the diet to the specific hormonal syndromecontrol diarrhea, flushing, hypoglycaemia or acid excess.
4. Protein intake, adequate calories, and targeted micronutrient supplementation are essential.
5. Collaboration between oncologists, surgeons, gastroenterologists and dietitians yields the best patientcentred outcomes.

For further reading, consult the latest guidelines from the North American Neuroendocrine Tumor Society (NANETS) and the European Neuroendocrine Tumor Society (ENETS), as well as peerreviewed articles on nutrition in endocrine malignancies.