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  • Diet and Cancer

  • Why is diet important in Cancer? 

  • Cancer and its treatments can sometimes make it more difficult to eat. This can lead to weight loss. If eating is difficult, it is important to try and focus on eating foods that are higher in calories and protein to help you keep your weight up.

    If you are being treated for cancer, eating well can help you:

    • Maintain your weight
    • Provide a source of energy
    • Help you deal with side effects from cancer treatment
    • Tolerate the most beneficial dose of certain treatments
    • Fight infection and recover faster from cancer treatment

    However, this does not necessarily mean eating healthily. A good diet when you are undergoing cancer treatment may take on a different meaning to when you are well and this may help you through your cancer journey. It is important that you eat enough to make sure your body gets all the nutrients it needs. Nutrition is an essential part of your cancer treatment and recovery, and overall it may help you to get through your cancer journey.

  • How does Cancer affect diet?

  • It can sometimes be difficult to eat enough with cancer. There are many reasons for this; it can be as a result of the cancer itself, or due to the side effects of the different treatments. Sometimes, weight loss may have happened before a diagnosis of cancer was made.

    • Type of cancer
    • Type of cancer treatment
    • Changes in nutrient metabolism
    • Psychological and emotional impact of cancer
  • Type of Cancer

  • The type of cancer can affect how well you are able to eat. If the site of the tumour (cancer) is in the upper part of the gut (mouth, oesophagus, stomach) this may affect the texture of the foods you can eat. If the tumour is in the lower part of the gut (intestines) this may affect your body’s ability to absorb and use nutrients normally.

  • Type of Cancer treatment

  • In many cases, the treatment of cancer involves one or more of the following treatments:

    • Chemotherapy
      • Chemotherapy is a type of treatment for cancer where medicine is used to kill cancer cells. Chemotherapy is given at regular intervals (cycles) and could last a number of months.
    • Radiotherapy
      • Radiotherapy or radiation therapy is the use of a type of x-ray to destroy cancer cells which leaves them unable to grow. It can be given either as:
        • external radiotherapy from outside the body using x-rays.
        • internal radiotherapy from a radioactive material placed within the body close to the tumour.
      • Surgery
        • Through surgery, the tumour and any nearby tissue that may contain cancer cells could be removed.
    • Biological therapy
      • Biological or targeted therapies are drugs that influence the body’s immune system to destroy cancer cells.

    Although these treatments are very effective at destroying cancer cells, some healthy cells are also damaged, such as those in the mouth, digestive tract, and hair follicles. This can lead to side effects, such as changes in taste, mouth sores, nausea, diarrhoea, and hair loss. More specifically, many of these side effects can cause eating problems that put some people off their food.

  • Changes in the body’s metabolism

  • In most types of cancer, the way the body uses nutrients can change. Tumours may produce chemicals that change the way the body uses or absorbs certain nutrients from food. As a result, the body’s use of protein, carbohydrates and fat may be affected.

    Cancer cachexia, also known as the ''wasting syndrome' is a condition where some of the following symptoms may be present: severe weight loss, loss of appetite, feeling sick, anaemia (low red blood cells), weakness and fatigue. Scientists do not fully understand why, however most believe that the cancer releases chemicals into the blood that contribute to the loss of fat and muscle. This may in turn speed up your metabolism, so that you burn off calories faster than normal. Therefore, even though you may be eating normally or even more than normal, you may still be losing weight as your body may be using up more calories (energy) than usual.

    If you suspect that you have cancer cachexia, make sure you seek the advice of your health care professional.

  • Psychological and emotional impact of Cancer

  • There are also emotional reasons why someone may not eat as much during cancer treatment. If you are living with a diagnosis of cancer you may be worried, or even struggling with its treatment. This can sometimes affect appetite and how much you feel like eating. If you are finding it difficult to cope, you may find it helpful to speak to someone who can help you with this. It is best to speak to your hospital team and they may be able to organise a referral to counselling services.

    The content of this page was reviewed by Saira Chowdhury
    Specialist Upper GI Oncology Dietitian
    Guys & St Thomas' NHS Foundation Trust
    January 2015