Cachexia is a metabolic disorder that can occur in approximately 80% of advanced cancers especially in gastrointestinal (GI) cancers such as pancreatic and colon, as well as lung cancers. Cachexia causes involuntary weight loss from a combination of factors including the loss of appetite (or anorexia), muscle wasting, a decrease in body fat, and an increase in metabolism. Muscle wasting is the characteristic symptom of cachexia and can lead to decreased strength and increased fatigue. There is also an increased risk of side effects from chemotherapy treatments in cancer patients who suffer from cachexia.
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Cancer’s effect on the body’s immune system may play a key role in cachexia by causing inflammation that affects the brain and skeletal muscle. For example, cancer’s inflammatory response may affect certain brain areas responsible for appetite causing a decrease in the desire to eat. Cancer-causing inflammatory responses may lead to an overall loss of muscle tissue by interfering with the body’s ability to build muscle while, at the same time, destroying healthy muscle.
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Cancer cachexia is divided into three clinical stages: pre-cachexia, cachexia, and refractory cachexia. When a cancer patient is pre-cachectic he/she will experience weight loss of less than 5% and anorexia. For a patient to meet the criteria for cachexia he/she must experience a 5% decrease in body weight over 6-12 months and have a body mass index (BMI) of less than 20 if under 65, and less than 22 if over 65. Once the patient reaches the refractory (unresponsive to treatment) stage of cachexia his/her life expectancy is less than 3 months and the primary focus of care becomes reducing symptoms and patient distress.
