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Cancer Health Center

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Nutrition in Cancer Care (PDQ®): Supportive care - Patient Information [NCI] - Effects of Cancer Treatment on Nutrition


Chemotherapy and Nutrition

Chemotherapy affects cells all through the body.

Chemotherapy affects fast-growing cells and is used to treat cancer because cancer cells grow and divide quickly. Healthy cells that normally grow and divide quickly may also be killed. These include cells in the mouth, digestive tract, and hair follicles.

Chemotherapy may affect nutrition.

Chemotherapy may cause side effects that cause problems with eating and digestion. When more than one anticancer drug is given, more side effects may occur or they may be more severe. The following side effects are common:

  • Loss of appetite.
  • Inflammation and sores in the mouth.
  • Changes in the way food tastes.
  • Feeling full after only a small amount of food.
  • Nausea.
  • Vomiting.
  • Diarrhea.
  • Constipation. (See the Constipation section for more information.)

Nutrition therapy can help relieve nutrition problems caused by chemotherapy.

Patients who have side effects from chemotherapy may not be able to eat normally and get all the nutrients they need to restore healthy blood counts between treatments. Nutrition therapy can help relieve these side effects, help patients recover from chemotherapy, prevent delays in treatment, prevent weight loss, and maintain general health. Nutrition therapy may include the following:

  • Nutrition supplement drinks between meals.
  • Enteral nutrition (tube feedings).
  • Changes in the diet, such as eating small meals throughout the day.

Radiation Therapy and Nutrition

Radiation therapy can affect cancer cells and healthy cells in the treatment area.

Radiation therapy can kill cancer cells and healthy cells in the treatment area. The amount of damage depends on the following:

  • The part of the body that is treated.
  • The total dose of radiation and how it is given.

Radiation therapy may affect nutrition.

Radiation therapy to any part of the digestive system often has side effects that cause nutrition problems. Most of the side effects begin a few weeks after radiation therapy begins and go away a few weeks after it is finished. Some side effects can continue for months or years after treatment ends.

The following are some of the more common side effects:

  • For radiation therapy to the head and neck
    • Loss of appetite.
    • Changes in the way food tastes.
    • Pain when swallowing.
    • Dry mouth or thick saliva.
    • Sore mouth and gums.
    • Narrowing of the upper esophagus, which can cause choking, breathing, and swallowing problems.
  • For radiation therapy to the chest
    • Infection of the esophagus.
    • Trouble swallowing.
    • Esophageal reflux (a backward flow of the stomach contents into the esophagus).
  • For radiation therapy to the abdomen or pelvis
    • Diarrhea.
    • Nausea.
    • Vomiting.
    • Inflamed intestines or rectum.
    • A decrease in the amount of nutrients absorbed by the intestines.
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