Weight Loss and Anorexia


Weight loss is a common complication of cancer and cancer treatments. Cancer or cancer treatments may first cause a loss of appetite or aversion to food, also known as anorexia, which then may lead to drastic weight loss.

What is anorexia?

Anorexia is a loss of appetite or aversion to food, which can lead to drastic weight loss. Anorexia can compromise your ability to get adequate nutrition through food sources. When you do not take in adequate calories and nutrients, your body is forced to “burn” fat and muscle, which is why you lose weight.

What causes anorexia in cancer patients?

Although not all cancer patients will develop anorexia and subsequent weight loss, anorexia and weight loss are very common. Anorexia may result from cancer, chemotherapy, radiation, or a variety of other causes, including physical and psychological causes.

Anorexia that is a direct result of the cancer occurs in the majority of patients with advanced-stage cancers. For these patients, the cancer has changed the way their metabolism works, dramatically impacting their weight. In addition, cancer can have psychological and social impacts that cause stress and changes in eating patterns. These changes can lead to anorexia and weight loss.

In many cases, cancer treatment, rather than the cancer itself, will cause anorexia. Both chemotherapy and radiation therapy cause a variety of side effects that can lead to anorexia and weight loss, such as nausea and vomiting, fatigue, changes in how things taste, and a dry mouth. In addition, cells in the body release tumor necrosis factor (TNF) and interleukin-1 in an attempt to fight the cancer, both of which cause anorexia. Destruction of cancer cells by radiation therapy increases levels of TNF and interleukin-1, resulting in anorexia and weight loss.

Why is it important to manage anorexia and weight loss?

Anorexia and the resulting weight loss compromises your health, often weakening your immune system and causing great discomfort and dehydration. As a result, cancer treatment may need to be reduced or delayed, which results in the delivery of treatment that is not optimal.

In an evaluation of 12 different studies involving 3,047 patients, the Eastern Cooperative Oncology Group found that loss of more than 5 percent of pre-cancer weight portended a poor prognosis for cancer patients. In addition, this weight loss was associated with a lower response to chemotherapy.

Not only can anorexia interfere with treatment, it can cause concern for both you and your family. Any attempts to prevent or manage anorexia can improve your health and provide you and your family with a sense of well-being.

How can anorexia and weight loss be managed?

The best way to manage anorexia and weight loss is to prevent them from occurring in the first place. However, sometimes these symptoms are inevitable results of cancer and cancer treatment. Some approaches that may help prevent anorexia and weight loss may include:

  • Controlling nausea and vomiting
  • Maintaining adequate nutrition
  • Stimulating appetite

Controlling Nausea and Vomiting

Both chemotherapy and radiation therapy cause nausea and vomiting, which can lead to anorexia and weight loss. The key to controlling nausea and vomiting is to prevent it before it occurs. Many new antivomiting drugs, called antiemetics, are very effective in preventing or decreasing nausea and vomiting. Antiemetics may be used alone or in combinations. Antiemetics are typically administered 24 hours before chemotherapy and then continued until 24 hours after chemotherapy. In addition, some patients may wish to consider nondrug methods to help with nausea and vomiting.

Nutritional Support

Since anorexia can compromise your ability to get adequate nutrition through food sources, you may benefit from treatment with nutritional support. All cancer patients should meet with a nutritionist or registered dietician before and throughout their treatment to help maintain their health through appropriate alterations to their diet.

Your nutritionist may recommend that you focus on eating higher calorie food, such as protein-rich food. For example, you may try including more of the following in your diet:

  • Protein drinks (powdered protein supplement mixed with fruit, milk, and/or yogurt)
  • Milk
  • Dairy products
  • Eggs
  • Meat
  • Sauces or gravies
  • Oil

In some situations, you may require caloric supplementation beyond what you can get through altering your diet. Nutritional support is beneficial to patients both before and during treatment. Nutritional support may be administered into the veins through parenteral nutrition, or directly into the intestines with enteral nutrition. Both of these types of nutritional support appear to be most beneficial to patients undergoing stem cell transplantation.

Total parenteral nutrition - Total parenteral nutrition refers to the intravenous (into your vein) delivery of a nutritionally adequate solution. Total parenteral nutrition is used for patients who cannot eat and may be beneficial in the perioperative setting for cancer patients with severe malnutrition; however, long-term of total parenteral nutrition for patients undergoing chemotherapy is strongly discouraged, as it does not appear to offer any benefit. Patients undergoing stem cell transplantation appear to receive the greatest benefit from total parenteral nutrition.

Enteral nutrition - Enteral nutrition refers to the delivery of nutrients directly into the gastrointestinal tract and is used when a patient cannot ingest, chew, or swallow food, but can digest and absorb nutrients. Enteral nutrition appears to be beneficial for patients undergoing stem cell transplantation.

Appetite Stimulants

A variety of appetite stimulants may help you to maintain adequate calorie and nutrient intake from food sources. These include Marinol® (dronabinol), Megace® (megestrol acetate), and dexamethasone.

Marinol: Marinol is part of a class of drugs called cannabinoids. Dronabinol, the active ingredient in Marinol, is produced in the laboratory and is a version of a naturally occurring substance in Cannabis sativa L. (marijuana). Dronabinol is known to be an appetite stimulant. Also, dronabinol is thought to directly block a receptor that is involved in chemotherapy-induced nausea and vomiting. Because of these two effects, dronabinol may be beneficial to patients receiving chemotherapy treatments.

In 139 patients with anorexia and weight loss, dronabinol significantly increased appetite after 4 weeks. There was a total increase in appetite of 38 percent for patients receiving dronabinol compared with 8 percent for patients receiving a placebo. The patients receiving dronabinol also tended to have decreased nausea and improved body weight and mood. Dronabinol has also been proven to reduce chemotherapy-induced nausea and vomiting in cancer patients.

Unlike marijuana, dronabinol provides standardized THC concentrations and does not contain the other 400 uncharacterized substances found in smoked marijuana, such as carcinogens or fungal spore. It is not associated with the quick high of smoked marijuana. However, you should not drive, operate machinery, or engage in any hazardous activity until it is established that you can tolerate the drug and perform such tasks safely. Dronabinol is FDA-approved and is administered orally in capsule form.

Megace (megestrol acetate) - Megestrol acetate is a progesterone, or steroid hormone, that improves appetite in patients with advanced cancer. Megestrol acetate is FDA-approved for the palliative treatment of advanced breast and endometrial cancer.

Several studies have established that megestrol acetate causes appetite stimulation and weight gain in cancer patients with anorexia. In a North Central Cancer Treatment Group trial, patients who received megestrol acetate experienced an increase in both appetite and nonfluid weight. Furthermore, 13 out of 15 placebo-controlled trials evaluating megestrol acetate demonstrated that it improves appetite in cancer patients.

Megestrol acetate is associated with some side effects. Megestrol acetate suppresses some endocrine functions and presents a slightly increased risk for thrombophlebitis, an inflammation of veins that is often accompanied by blood clots. Patients receiving megestrol acetate who experience serious infection or trauma may require supplemental corticosteroids to reduce inflammation.

Dexamethasone: Dexamethasone is a corticosteroid that is often prescribed for cancer-associated anorexia. Corticosteroids are substances produced by the adrenal gland, which serves important functions in the body, including regulating metabolism and reducing inflammation. In a randomized, placebo-controlled trial, dexamethasone was found to improve appetite in patients with advanced cancer. A study that compared several different drugs that stimulate appetite indicated that dexamethasone and megestrol acetate produced equivalent improvement in appetite. However, dexamethasone was associated with significantly worse side effects, such as myopathy, which is an abnormal condition of the skeletal muscle characterized by muscle weakness and other changes in the muscle tissue. As a result, dexamethasone is not recommended for chronic use, but appears to be beneficial for some cancer patients with a poor prognosis, as serious side effects are unlikely to occur in the short term.

This content was last reviewed August 15, 2010 by Dr. Reshma L. Mahtani.
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