Nutrition in Cancer

Cancer and nutritional needs

Apart from a poor appetite and loss of weight, some people with cancer have other difficulties eating. Some of these problems may relate to the cancer itself, some relate to medications, the treatment and its side effects. Due to the body’s response to tumours the way the body uses nutrients is sometimes changed in people with cancer.

Tumours may produce chemicals that change the way the body uses certain nutrients or absorb nutrients from food. The body's use of protein, carbohydrates, and fat may be affected, especially by tumours of the stomach or intestines. Therefore, often sick people may appear to be eating enough, but the body may not be able to absorb all the nutrients from the food.

In the majority of cases, treatment of cancer involves therapies that destroy cancer cells growing in the body. The most common treatments, used alone or in combination, are surgery, Chemotherapy, Radiotherapy, hormone therapy, and immunotherapy (or biological therapy). Although all of these methods are very powerful in the process of killing the cancer cells, some healthy cells are also damaged, especially those normally growing and dividing rapidly, such as those in the mouth, digestive tract, and hair. This is what causes side effects of cancer treatment, and this in turn can affect nutritional needs. The nature, severity and degree of side effects will vary from person to person and rely on many factors including the type of cancer you have, the part of your body being treated, the type and length of treatment, and the dose of treatment. Side effects can often be well-controlled and most of them go away after treatment ends.

Some side effects of cancer therapy can further affect eating habits: dietary problems already present may be aggravated; Nausea and sickness can cause loss of appetite and taste alterations can make certain foods less appealing. As a result, cancer patients may eat less and may have trouble consuming enough of a wide variety of foods to satisfy nutritional needs.

Eating too little protein and calories is the most common nutrition problem facing many cancer patients. Protein and calories are important for healing, fighting infection and providing energy. Other deficiencies experienced by cancer patients are vitamins (Folate, Vitamin A, Vitamin C, and Vitamin D) and minerals (Copper, Iron, Magnesium, Zinc, and Calcium).

Cancer side effects - why do they occur?

All the methods of treating cancer — surgery, radiotherapy, chemotherapy, hormone therapy and biological therapy (immunotherapy) — are very powerful in killing cancer cells, targeting the fast-growing cancer cells in the body.

Unfortunately, healthy cells can also be damaged. Healthy cells that normally grow and divide rapidly, such as those in the mouth, digestive tract and hair are often affected by cancer treatments. The damage to healthy cells is what produces the unpleasant side effects that cause eating problems.

Principal side effects that can affect your ability to eat include:

* loss of appetite
* sore mouth or throat
* dry mouth
* dental and gum problems(which can occur as a result of treatment or due to weight loss)
* changes in sense of taste or smell
* nausea/vomiting
* diarrhoea
* lactose intolerance
* constipation
* fatigue and/or depression

You may or may not have any of these side effects. Many factors determine whether you will have any and how severe they will be. These factors include the type of cancer you have, the part of your body being treated, the type and length of treatment, and the dose of treatment. The good news is that if you do have side effects they can often be well controlled. Most side effects also go away after treatment ends. Your doctor or nurse can tell you more about your chances of having side effects and what they might be like.

Complications associated with your cancer or treatment can be acute or chronic.

* Acute complications are those that occur during therapy. Chemotherapy usually causes acute complications that heal after treatment ends.
* Chronic complications are those that continue or develop months to years after therapy ends. Radiation can cause acute complications but may also cause permanent tissue damage that puts the patient at a lifelong risk of oral complications.

Nutrition in advanced cancer

People in the advanced stages of cancer may have been told that their cancer has spread, come back or perhaps that it cannot be cured. When cancer is not curable, treatment becomes palliative, i.e. focusing on the relief of symptoms rather than treating their cause. Patients may have palliative treatment (e.g. Radiotherapy or Chemotherapy) to help control their cancer symptoms and they will experience the same side effects and subsequent nutritional problems as someone undergoing curative treatment. Nutritional advice for Palliative Care patients is very similar to that offered to patients having curative treatment, but the goal of treatment will be aimed more at improving Quality of life and providing relief from symptoms. Common symptoms experienced by patients with advanced cancer are anorexia (reduced appetite) and weight loss. Weight loss is often expressed as a concern by both patients and their families, as changes in appearance can serve as a constant reminder of the diagnosis of cancer. Patients with advanced cancer may develop cachexia. Cancer cachexia is the term used to describe a complex syndrome that is characterised by progressive, involuntary weight loss. You may also hear this called ‘wasting syndrome’. Both a reduction in food intake and a change in the body’s metabolism are thought to contribute to the development of the following symptoms:

* Weight loss, even in patients that are eating well
* The loss of fat and muscle mass (muscle wastage)
* Anorexia
* Early satiety (feeling full after eating small amounts)
* Weakness and fatigue

Cachexia seems to be more common in people with lung cancer or with cancers in the digestive system. Nutrition related side effects might occur or become worse as cancer becomes more advanced. The following symptoms are some of those commonly experienced by people with progressive illness:

* Loss of appetite
* Weight loss
* Early satiety
* Sickness
* Bowel changes e.g. constipation or diarrhoea
* Bloating
* Dry mouth
* Sore mouth
* Taste changes

Some people may have particular eating problems caused by the local effects of their cancer e.g. swallowing difficulties resulting from oesophageal (gullet) cancer. Individual assessment of the patients’ dietary needs may be helpful here. Patients can ask their Hospital Doctor or GP to refer them to a Registered Dietician who can offer specialist advice.

The psychological effect of having advanced cancer can be deeply worrying for patients and this may further impair their desire to eat or drink.

Many of these symptoms can be improved, and so it is essential that patients discuss them with their Doctor or Healthcare professional. Achieving good symptom control will benefit food intake.

When cancer is advanced, food should be encouraged as a source of enjoyment and it may be appropriate for any dietary restrictions (e.g. diabetic diets) to be stopped or relaxed. Any changes in diet need to be discussed with the patients’ medical team first who can offer advice, support and reassurance.


This information is reproduced with the kind permission of Andi Fey,

This page was last modified on 20 March 2009 at 21:48.