The side effects of cancer and cancer treatment that can affect eating include:
Cancer and cancer treatments may affect taste, smell, appetite, and the ability to eat enough food or absorb the nutrients from food. This can cause malnutrition (a condition caused by a lack of key nutrients). Malnutrition can cause the patient to be weak, tired, and unable to fight infections or get through cancer treatment. Malnutrition may be made worse if the cancer grows or spreads. Eating too little protein and calories is a very common problem for cancer patients. Having enough protein and calories is important for healing, fighting infection, and having enough energy.
Anorexia and cachexia are common causes of malnutrition in cancer patients.
Anorexia (the loss of appetite or desire to eat) is a common symptom in people with cancer. Anorexia may occur early in the disease or later, if the cancer grows or spreads. Some patients already have anorexia when they are diagnosed with cancer. Almost all patients who have advanced cancer will have anorexia. Anorexia is the most common cause of malnutrition in cancer patients.
Cachexia is a condition marked by a loss of appetite, weight loss, muscle loss, and general weakness. It is common in patients with tumors of the lung, pancreas, and upper gastrointestinal tract. It is important to watch for and treat cachexia early in cancer treatment because it is hard to correct.
Cancer patients may have anorexia and cachexia at the same time. Weight loss can be caused by eating fewer calories, using more calories, or both.
It is important to treat weight loss caused by cancer and its treatment.
It is important that cancer symptoms and side effects that affect eating and cause weight loss are treated early. Both nutrition therapy and medicine can help the patient stay at a healthy weight. Medicine may be used for the following:
- To help increase appetite.
- To help digest food.
- To help the muscles of the stomach and intestines contract (to keep food moving along).
- To prevent or treat nausea and vomiting.
- To prevent or treat diarrhea.
- To prevent or treat constipation.
- To prevent and treat mouth problems (such as dry mouth, infection, pain, and sores).
- To prevent and treat pain.
See the Nutrition Therapy in Cancer Care section and the Treatment of Symptoms section for more information.