For most people with cancer, loss of appetite or change in appetite is a common clinical symptom adding to the weight loss seen in cancer patients from poor food intake. Cancer burden on patients is usually severe enough to cause nutritional imbalances leading to weight loss and nutritional deficiencies, but this is worsened with the onset of appetite loss.
What is anorexia?
Loss of appetite (anorexia nervosa) is defined as the loss of interest in eating by an individual and several factors come to play in making food unpleasing to the individual.
The loss of over 10% of pre-cancer weight is term cachexia, and it occurs in over 70% of patients with advanced cancer irrespective of the organ of origin of such cancer. It is characterized by the following:
- Severe breakdown of adipose fats and muscle protein
- Severe weight loss
- Profound body weakness
- Increase metabolism of the body
- Poor prognosis/outcome.
The loss in muscle mass and adipose tissue is as a result of:
- An increase in the metabolic rate of the body
- Poor food intake and poor synthesis of new muscle proteins
- Fat deposition is within the subcutaneous tissues of the body.
Loss of appetite translates to a reduction in food intake and subsequently weight loss.
In cancer patients, a reduction in food intake has been related to disorders in taste (controlled by the taste buds of the tongue) and central control of appetite (feeding centers in the brain). But the effect of cachexia cannot be fully explained based on a reduction in food intake.
Factors Affecting Appetite in Cancer Patients:
The exact mechanism by which cancer causes loss of appetite is not yet fully understood by physicians, but several factors have been shown to affect food intake and appetite in cancer patients. Cancer affects appetite in the following ways:
- Cancer cells secrete chemical mediators such as cytokines, e.g. tumor necrosis factor (TNF) interferon β (IFN β) and interleukins (IL-1). They suppress the feeding centers in the brain thus making food unpleasant to the patient. These chemical mediators also increase the metabolic rate of the body and with poor calorie intake. The body starts to break down fat and also muscle proteins with the aim of meeting up with the metabolic demand of the body thus causing severe weight loss and wasting seen in cancer patients
- The stomach acts as the storage house for consumed food, and it also aids in the digestion of food. Cancer of the stomach reduces space within the stomach thus limiting the amount of food consumed. The space occupying effect of stomach cancer gives a false sense of fullness and satiety thus affecting appetite and food intake
- Esophageal cancers and oral cancers cause feeding difficulties. Feeding is uncomfortable and painful thereby affecting food intake by such patients. The reduction in appetite and food intake is from the local effect of esophageal and oral cancers. For example pain in chewing and swallowing, obstruction of the esophagus, a presence of oral sores, dental anarchy, and pain.
- Brain tumors can originate from areas that control food intake in the brain or such tumors arising from the brain can grow to compress on the feeding centers of the brain. It affects appetite and food intake causing weight loss associated with brain cancers
- Accumulation of fluid within the abdominal cavity or the enlargement of the spleen may compress on the stomach hence reducing the capacity of the stomach to accumulate food. These give a sense of fullness which affects food intake
- Radiotherapy and chemotherapy used in the treatment of cancer have potential side effects that can affect appetite. Such side effects are mouth ulcers, dry mouth, nausea and vomiting, intense inflammation of the intestines and other abdominal organs. These side effects may affect the appetite of the patient.
Symptoms caused/ exaggerated by loss of appetite
- Loss of appetite causes the patient to consume less food that is not sufficient to provide calories to the body and to sustain the metabolism of the body. It is worth mentioning that cancer burden increases the calorie demand on the body
- Excessive weight loss
- Generalized body weakness and fatigue. Most patients also experience exercise intolerance
- Presence of low-grade fever due to increased metabolic rate, cancer burden or infection
- Severe muscle wasting and asthenia (lack of energy and weakness)
- Inability to control body temperature leading to abnormal body temperature.
- In the presence of anemia (low red blood cells) due to nutritional deficiency e.g. iron, folic acid, and vitamin B12 deficiencies, increase breakdown of (RBC) red blood cells and ineffective red blood cell production from bone marrow suppression
- Hypotension accompanies weight loss.
- Micronutrient deficiency with their antecedent problems
- The features of chronic malnutrition that are loss of hair, facial swelling or puffiness, protruding abdomen in children, irritability and lethargy, diarrhea.
Effects of weight loss Due To Anorexia (loss of appetite)
- Respiratory failure and insufficiency: the act of breathing is an active process that involves the use of respiratory muscles i.e. the intercostal muscles. In cancer patient with weight loss, the intercostal muscles are weakened by excessive muscle protein breakdown leading to respiratory insufficiency and respiratory failure. Respiratory failure is currently the leading cause of death in most cachexia patients. Other complications are recurrent chest infection (pneumonia) and aspiration
- Heart: the heart is made up of cardiac muscles which is a specialized group of muscles that ensures that the heart beats adequately. In cancer patients with loss of appetite and weight loss, there is increase protein breakdown that also affects the cardiac muscles leading to a heart that is weak and with dilated chambers.
- Intestines: the intestines are specialized adapted for the absorption of nutrients. Chronic loss of appetite and weight loss affects the absorptive capability of the intestines hence worsening the nutritional deficiency seen in cancer patients.
Both appetite loss and intake of food should be assessed in cachectic patients since conscious control of eating may overcome appetite loss sometimes. It is important for a patient suffering with cancer to control their weight even if their appetite has changed in cancer.
Proper nutrition helps your body to fight disease and cope with the effects of cancer treatment.