oncolex logo
Utskriftsdato (4.3.2021)

Nutritional status and radiation therapy

Medical editor Karianne Spetaas Johansen
Clinical Nutritionist
Oslo University Hospital


Many head/neck patients are at risk for developing malnutrition, which is associated with increased morbidity and illness. Malnutrition is more difficult to treat than to prevent.

Monitoring nutritional status is an important part of treatment. The goal is to identify malnutrition as early as possible in order to initiate measures quickly. 

Radiation therapy is often intensive and causes side effects such as dry mouth, pain, mucositis, and taste disturbance. 


  • Radiation therapy to the head/neck region.


  • Maintain nutritional status in the period of acute side effects caused by radiation therapy.


Weight loss is one of the most important signs of change in nutritional status. A weight loss of more than 10% over the past 6 months or more than 5% over the last 3 months is a significant and serious weight loss. If the weight loss occurs in combination with low BMI (body mass index) (< 20 kg/m2 for adults) and/or a food intake of less than 60% of the calculated requirement over the past 10 days, the patient will be malnourished or be at nutritional risk.

Calculation of nutrition and fluid requirements

  • Ambulatory patients: 30-35 kcal/kg/day
  • Bed-ridden patients: 25-30 kcal/kg/day
  • Elderly above 70 years: Recommended amount is reduced by 10%
  • Fluid requirement: 30-35 ml/kg/day  

Actions include offerring the patient a diet that is appropriate for their symptoms and nutritional status. The patient should be offered nutritionally-rich food, snacks, nutritional beverages, tube feeding, and intravenous nutrition.  

Small, frequent meals

Patients must often have food of softer consistency and milder in taste. This requires the food to be as rich in nutrition as possible. These patients will need 6-8 small meals per day to meet their energy need.

Enrichment of food and beverages

The most effective way to enrich food and drink is to use ordinary foods such as cream, oil, butter, sour cream, mayonaise, etc. 

Enrichment of food and drink is done to increase the energy content of the meal without increasing the volume. This is done for patients who eat too little and therefore need energy-rich food. 

Enrichment powders

  • are not supplemented with vitamins, minerals, or trace elements
  • are supplemented usually with only fat, carbohydrates, or protein (sometimes a combination of fat and carbohydrates). 

Some powders are nutritionally complete, that is, a given amount includes everything the body needs of energy and vitamins and minerals. There are also powders neutral in taste which do not affect the taste or consistency of food. 

Nutrional beverages

Nutritional beverages may be used as a meal in itself or between meals. Nutritional drinks can be a more valuable snack than "normal" food, because it is often easier for the patient to drink than to eat. It has been shown that if nutritional drinks are introduced as snacks, it does not affect the energy intake during the main meals.

There are a number of ready-made nutritional drinks on the market. Some of the products are of nutritionally complete. They contain carbohydrates, protein and fat and are supplemented with all the necessary vitamins, minerals and trace minerals and possibly fiber. Some of these products can be used as the sole source of nutrition. The energy content varies from 85-200 kcal/100 ml and some products have a high protein content.

The products are also adapted for age, and the dose is determined individually by a clinical dietician/doctor.

Many patients prefer homemade nutritional drinks based on full fat milk, cream, ice cream, fruit and possibly flavor supplements. These are free of additives and have a fresher taste. The energy and protein content is close to the commercial products and at the same time they are more sensibly priced.

Tube feeding

Tube feeding is preferable to total parenteral nutrition (TPN) when the digestive system is working. Nutrition supply to the intestine is more physiological. It protects against bacterial growth, maintains the intestine's mucous membrane structure and function, and promotes motility. Tube feeding involves less risk of metabolic complications.

Tube feeding is used in the event of

  • insufficient food intake (less than 60% of energy requirements) over the past 5-7 days despite oral intake
  • weight loss >2 % over the past week, >5 % over the past month or >10 % over the past 6 months
  • danger of weight loss due to planned treatment
  • low albumin values (under 35 g/l, lower limit for normal area)
  • stenosis with feeding obstacles in pharynx/gullet

Tube feeding must not be used for the following conditions.

  • Paralysis or ileus of the alimentary tract
  • Short bowel syndrome
  • Serious diarrhea
  • Serious acute pancreatitis
  • Obstruction of the intestine
  • Serious fluid problems

Tube feeding solutions

The tube feeding solution must be nutritionally complete because they are used as the sole source of nourishment. The most frequently used are standard (1 kcal/ml), or energy-rich (1.5 kcal/ml) solutions with or without fiber. There are also tube feeding solutions adapted for patients with digestion and absorption problems, patients with diabetes or lactose allergy, and intensive care and cancer patients.

Parenteral ernæring

Parenteral nutrition should only be used if food by mouth or tube feeding cannot be maintained. Parenteral nutrition can also be used as a supplement to tube feeding or ordinary food if the patient's nutrional needs are not met by this alone.

Precautions must be taken for the following conditions:

  • Renal failure
  • Heart failure
  • Lung failure
  • Large fluid or electrolyte loss
  • Diabetes mellitus
  • Liver failure 


Subjective Global Assessment (SGA)

Subjective Global Assessment (SGA) is a scheme for classifying the patient's nutritional status.

Based on information about weight, food intake, symptoms and physical function, the patient is classifed as well-nourished, somewhat undernourished, or seriously malnourished. This categorization as shown to correlate well with more objective goals for nutritional status as well as morbidity, death, and quality of life. 

Other tables that are frequently used are Malnutrition Universal Screening Tool (MUST), Mini Nutritional Assessment (MNA) and Nutrition Risk Score (NRS). In principle, these schemes are prepared in the same way as SGA, but they are not validated for patients with cancer.

Actions include offerring the patient a diet that is appropriate for their symptoms and nutritional status. The patient should be offered nutritionally-rich food, snacks, nutritional beverages, tube feeding, and intravenous nutrition.

Tube feeding

The end of the tube is often inserted into the stomach. In the event of poor gastric function, total gastrectomy or pancreatic resection, the feeding tube should be inserted in the duodenum or jejunum. The position of the feeding tube is vital for the choice of tube feeding solution and mode of administration.

The most common method is to insert the tube nasogastrically, but it can also be done through the abdominal wall (PEG).

Parenteral ernæring

Peripheral veins can be used for short-term parenteral nutrition. In this case, a large vein on the forearm is used and a small needle. Nutrition is then given as more diluted solutions.

Central veins must be used for TPN with high osmolality.


All patients are weighed regularly (1–2 times each week). This is a prerequisite to being able to register changes in the nutritional status.

Tube feeding

Tube feeding is given continuously with a low drop rate or by interval/bolus administration (individually adapted meals with high drop rate).

When the patient's energy and fluid requirements are fulfilled, it will be decided whether the patient will be given bolus or continuous supply at night, in order to increase mobilization during the day. However, this requires that the patient does not have diarrhea, nausea or other complaints associated with the supply of nutrition.

For a running feeding tube:

  • Every 4-8 hours, it should be aspirated in order to monitor the gastric emptying. This applies especially to immobile and weak patients.
  • Weekly or more often, the nutrition program/fluid balance, evaluation, edema control, blood tests (albumin, K, Mg, P, blood glucose) should be monitored weekly or more often.
  • Every 6 weeks, the tube should be changed. Alternate nostrils avoid irritation in the nose through prolonged feeding.  

If it is not possible to administer drugs orally, it can be done via a tube. It is recommended to use drugs available in fluid form. Tablets can also be crushed and dissolved in water or gluocose water.

Experience shows that the use of infusion pumps causes fewer side effects and ensures correct volume and rate.

Bolus supply

Initiation of tube feeding with bolus supply is only recommended

  • if the patient been taking any food until the last 24 hours
  • if the patient is taking some food and requires tube feeding for additional nourishment

It is recommended to use pumps for bolus supply for the first 1–2 days.

Continuous supply

If the patient cannot tolerate bolus supply (vomiting, abdominal discomfort, nausea, diarrhea), reverting to continuous supply should be considered.

Tube feeding should always be administered continuously to very malnourished patients or if the tube end is located distally to the pylorus.

Parenteral ernæring

If the patient has a satisfactory nourishment status, begin with 100% of the requirement. If the patient is seriously malnourished and at risk for refeeding syndrome, renourishment should start slowly (10 kcal/kg/day), thereafter increasing slowly to 100% over 4-7 days. 

The patient must be monitored closely in relation to

  • electrolytes (potassium, phosphate and magnesium).
  • infusion rate.
  • twenty-four hour urine sample and fluid balance should be calculated daily.
  • glucose in the blood and urine, and electrolyte in the blood should be examined daily at the start.
  • liver tests, kidney function tests and triglycerides should be taken examined at least once every week.

For TPN treatment longer than 1 month, vitamins and trace elements should be examined.


The patient's nutrition status should be monitored at follow-up visits after the end of treatment.