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.

Source: National Cancer Institute