Martin E. Liebling, M.D., FACP
Loss of appetite occurs commonly among cancer patients. Anorexia is an abnormal loss of appetite that often results in severe weight loss. It affects patients with many different diseases, and is the leading cause of malnutrition in patients with cancer. Anorexia is not the same as anorexia nervosa, an eating disorder that is one form of anorexia.
Loss of appetite can develop when cancer causes pain, nausea, vomiting, diarrhea, constipation, sore or dry mouth, difficulty swallowing or other symptoms. Many cancer treatments, such as chemotherapy and radiation therapy, also cause some degree of appetite loss, as do stress, anxiety and depression related to cancer.
Anorexia can lead to a condition called protein-calorie malnutrition (PCM), and severe cases can result in cachexia, a form of malnutrition. This is especially dangerous for cancer patients, who need proper nutrition to give their bodies strength to fight the disease and cope with its treatments.
Loss of appetite is present in 15 to 25 percent of all cancer patients at the time of diagnosis, according to the National Cancer Institute. Patients are often referred to a registered dietitian, to help them cope with their nutritional problems. In many cases, the dietitian will be part of the patient’s cancer care team. These professionals can help plan meals that are appealing, as well as rich in nutrients and calories, to meet the needs of the cancer patient. They can also provide recommendations for dealing with the side effects of cancer or its treatments that can lead to anorexia.
Patients with anorexia may need medications to help stimulate their appetite. However, some patients may be at risk for malnutrition even when eating properly. This is because cancer can also affect the body’s ability to properly absorb nutrients. In such cases, patients may need to receive nutrition via a feeding tube or intravenously to ensure adequate nutrition.
About appetite loss & cancer
Appetite loss, is common among cancer patients. Anorexia is a decrease in or complete loss of appetite that causes significant weight loss in patients with cancer and other diseases. It can occur as a result of cancer, or as a side effect of its many treatments, including surgery, chemotherapy, biological therapy, radiation therapy and hormone therapy. Anorexia is an almost universal side effect in patients who have widely metastatic (spreading) cancer. Anorexia should not be confused with anorexia nervosa, a primary eating disorder that is one form of anorexia.
Nutrition is the process by which all living organisms assimilate food and use it for growth, energy and for replacement of tissues. Food is chewed and swallowed before it enters the esophagus, a tube-shaped organ that transports food down through the neck and chest and into the stomach.
Nutrients are absorbed into the body during the digestive process. This begins within the stomach, where gastric juices are secreted and mixed with the food into a thick fluid. This fluid is then emptied into the small intestine and further broken down before the nutrients are absorbed into the body.
Improved nutrition has many benefits, including:
- Maintains healthy levels of body weight and strength
- Prevents body tissues from breaking down
- Repairs damaged tissue
- Fights infection
- Improves patient’s long-term prognosis
Cancer patients with appetite loss are frequently diagnosed with protein-calorie malnutrition (PCM), which results from insufficient intake or absorption of carbohydrates, proteins and fats. Patients with this condition do not consume or absorb enough nutrients to meet their body’s metabolic requirements. Changes in the metabolism contribute to loss of skeletal muscle and adipose tissue (fat).
Poor nutrition deprives patients of the strength their bodies need to fight cancer and to withstand the rigors of cancer treatments. Researchers have found a correlation between weight loss and poor prognosis for cancer patients. Poor nutrition can increase the likelihood and severity of side effects associated with treatments, and can increase the risk of infection.
In its most severe form, anorexia and PCM can lead to cachexia, a type of malnutrition that can result in weakness and a substantial, progressive loss of body weight, fat and muscle. Cachexia is suspected in cancer patients who have an involuntary weight loss of greater than 5 percent of their precancer weight within a six-month period. When anorexia triggers cachexia, it is known as the anorexia-cachexia syndrome. About 50 percent of cancer patients suffer from this syndrome, according to the American Cancer Society.
Patients with solid tumors are at particular risk for cachexia. For example, cachexia is associated with cancers of the lung, breast and pancreas.
Cachexia is less likely in patients with blood cancers such as leukemia or multiple myeloma.
Cachexia differs from starvation. A healthy person’s body can adjust to starvation by slowing down its use of nutrients. However, the body of a cancer patient does not make this adjustment. As a result, cachexia is identified as the immediate cause of death in 20 percent to 40 percent of cancer patients, according to the National Cancer Institute.
Loss of appetite belongs to a class of manifestations known as nutrition impact symptoms. These are symptoms that affect appetite or impede oral intake. They include:
- Mucositis (inflammation of any mucous membrane, including the mouth)
- Dysphagia (swallowing impairment)
- Alterations in taste and smell
Potential causes of appetite loss
Loss of appetite can have potentially devastating consequences to the health of cancer patients. It may result from several factors. For instance, the following symptoms associated with cancer may make patients less hungry and lead to appetite loss:
- Nauseaand vomiting
- Difficulty swallowing (dysphagia)
- Changes in taste and/or smell
- Premature satiety (fullness)
- Diarrhea or constipation
- Sore or dry mouth
- Anxiety, stress or depression
Cancer treatments also may cause some degree of anorexia in patients. Such treatments include:
- Radiation therapy
- Hormone therapy
- Biological therapy
In addition to killing cancer cells, these treatments typically destroy some healthy cells. This can trigger side effects that lead to anorexia, such as premature satiety (fullness), changes in taste and smell that make food less appealing, dry mouth, nausea, vomiting and others.
Two primary factors related to cancer make it more difficult for patients to process nutrients:
- Metabolic changes. Cancer can physiologically alter the body’s metabolism, the chemical processes necessary for the maintenance of life. Patients may experience an increased basal metabolic rate (measure of the rate at which a person’s body “burns” energy) and an increased overall total energy expenditure. This means that patients must eat more to provide the calories necessary to replace the lost calories.
- Malabsorption. For a number of reasons, cancer patients are less likely to properly absorb nutrients. In some cases, the cancer itself may cause these problems. For instance, pancreatic cancer may cause a decrease in the production of the digestive juices that regulate absorption. In other cases, surgery to correct a problem can affect the absorption of nutrients. For example, this might occur in patients who have undergone stomach resection as a treatment for stomach cancer.
These factors may require patients to consume more calories to maintain their current weight and body mass, known as body mass index (BMI). BMI is a calculation of a person’s body fat relative to their height and weight. Patients need to maintain an appropriate BMI for optimal health. However, anorexia makes this difficult because it deprives patients of the appetite necessary to consume enough foods to maintain their weight.
As a result of this combination of appetite loss and metabolic changes, cancer patients frequently experience significant weight loss, usually defined as at least 10 percent loss of body weight over a period of six months. For example, by the time of diagnosis, 80 percent of patients with upper gastrointestinal cancer and 60 percent of patients with lung cancer have experienced significant weight loss, according to the National Cancer Institute.
Treatment and prevention of appetite loss
Cancer patients must pay special attention to their diet to avoid suffering from appetite loss. They need to consume foods and drinks that are rich in key nutrients, such as vitamins, minerals, protein, carbohydrates and fat. If a patient appears to be losing weight, a physician will review the patient’s medical history and perform a physical examination. If anorexia is diagnosed, the patient will work with members of the cancer care team to ensure that adequate nutrition levels are maintained.
A registered dietitian can help patients plan appropriate meals by providing a nutrition screening and comprehensive diet recommendations. This should continue throughout a patient’s cancer treatment, as circumstances may change over time. For example, patients receiving treatment for early-stage cancers may experience excessive weight gain during chemotherapy. In contrast, most patients in later stages of cancer are more likely to experience significant weight loss.
To prevent weight loss, patients may be placed on high-calorie diets. Protein content may be boosted to prevent muscle wasting. Foods that may be included in the patient’s diet are peanut butter, dairy products high in fat and meats.
In some cases, cancer patients find it difficult to consume fats and may require a low-fat, high-protein diet. Such foods include lean meats and low-fat dairy products, such as yogurt and cottage cheese.
Patients also are encouraged to eat a variety of fruits and vegetables. Fruit juices and dried fruits are good sources of nutrients that are also packed with calories. Calorie-dense vegetables include corn, peas, potatoes and squash.
Many cancer patients complain that treatments change their sense of taste and smell. In some cases, sweet foods taste sour, sour foods taste sweet and meats taste bitter (due to the release of proteins in the mouth). Chemotherapy and radiation therapy can also leave patients with a metallic taste in their mouths. All of these factors can result in a loss of appetiteand decreased intake.
Patients can take several steps that may help lessen these undesirable effects, including:
- Brush teeth several times daily. Mouth rinses such as diluted bicarbonate of soda can also be helpful.
- Sweeten foods and beverages. Bitter sensations can be lessened by adding sweet fruits, honey or artificial sweeteners such as aspartame.
- Use substitutes for meat. Bland chicken or fish, eggs, mild cheeses, or tofu may taste less bitter than meat. These foods may taste better in casseroles or stews. Marinating these foods can help as well.
- Add flavorings to foods but avoid spicy, highly seasoned foods.
- Use butter or margarine on starchy foods. This helps improve the taste of bread, potatoes and rice and also adds fat and calories.
- Try foods that previously seemed unappealing. Because of the taste changes associated with chemotherapy, patients may find that they enjoy foods they previously disliked.
- Eat smaller meals throughout the day, rather than three big meals. Patients may find this is easier both in terms of their desire to eat and their body’s ability to adequately process foods. Snacks also may help patients with bouts of nausea while providing calories. For patients who are unable to tolerate solid foods, high caloric or protein drinks may serve as a supplement to meals.
- Keep a diet log. Recording the foods consumed can help the patient and dietician determine the nutritional intake. A log can also help patients keep track of the items that are better tolerated for future meal planning. In turn, it can help eliminate the foods that might cause side effects, such as nausea or diarrhea.
- Consult with other cancer patients and support groups. Individuals who have dealt with cancer may provide valuable recommendations from personal experiences. These suggestions may help patients who are currently suffering from the same complications.
In some cases, patients may need prescribed medications to help stimulate their appetite. Such medications include:
- Prednisone. A corticosteroid hormone.
- Megestrol acetate. Synthetic relative of the female hormone progesterone.
- Marinol. A legally available synthetic form of marijuana that is delivered in capsule form.
There are some cancer patients that eat properly, but still become malnourished. This may be due to an inability of the body to properly absorb nutrients. In such instances, patients may need to be placed on a feeding tube to ensure that they receive adequate nutrition. There are several forms of feeding tubes that can be used depending on the needs of the patient.
One tube, known as a nasogastric tube (NG tube) is placed in the nose, through the throat and into the stomach. This thin, flexible tube allows specially formulated liquid nutrition to enter the stomach through the tube in the nose. Patients can still eat through their mouths, with the feeding tube used only when necessary. Tube feedings can usually be taken at home and can be performed by the patient or caregiver with training. In some cases, a more permanent tube may be surgically placed directly into the stomach (gastrostomy) or the intestines (jejunostomy). Liquid feedings may be provided through the tube as the primary source of nutrition or to supplement what is eaten by the patient. When the tube is no longer needed for nutrition, it can be removed by a physician.
Other patients may receive nutrient solutions that are injected directly into a vein. This is known as hyperalimentation or total parenteral nutrition (TPN), and it is typically used for a shorter duration than a feeding tube. Circumstances that might require this type of nutritional support include:
- Surgery of the digestive system
- Complete blockage of an intestine
- Severe vomiting and diarrhea
- Complications that prevent eating or use of a feeding tube
- Temporary complications expected to resolve in a short period of time
Finally, lack of appetite in cancer patients is sometimes related to emotional factors, such as depression. Patients will be monitored for emotional problems and may be referred to a mental health professional if necessary. In some cases, an antidepressant may increase a patient’s appetite.
Anorexia is easier to control if it is treated early. Many patients with the form of malnutrition known as cachexia do not experience a complete reversal of the syndrome, even after undergoing aggressive nutrition therapy. For this reason, it is important for cancer patients to use nutrition monitoring and plan to prevent cachexia before it occurs.
Patients with anorexia may experience different outcomes. For example, patients who experience anorexia during cancer treatments find it to be mild, and often gain their appetite within weeks after they end treatments. Other patients may experience more severe symptoms and have increased problems with maintaining their nutrition and health. The patient’s cancer care team can help determine the best plan of treatment and provide individual recommendations.
Questions for your doctor
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor or healthcare professional the following questions about appetite loss and cancer:
- How will I know if I am becoming malnourished?
- Which tests will I need to determine the cause of my malnutrition?
- What are the chances I will develop anorexia with my type of cancer?
- Are there any ways I can prevent developing anorexia?
- Will my treatments likely interfere with my eating and nutrition?
- What can be done if I experience difficulties tolerating food?
- Are there nutritional supplements that I can take?
- If I have a poor appetite, which drugs might help me?
- Will my appetite return after my cancer treatments?
- What factors will determine if I need a feeding tube?
- If I need a feeding tube, what type will I have?
- Can you refer me to a dietician who can help me with my meals?