Cachexia is a syndrome that is characterized by symptoms of unintentional weight loss, progressive muscle wasting, and a loss of appetite. Present in at least 50% of people with advanced cancer, it's estimated that it contributes directly to 20% of cancer deaths.
Even though the symptoms and signs of cachexia are usually noticed late in the course of cancer, we're learning that the process leading to muscle wasting begins very early on after a diagnosis of cancer. In such, cachexia is often present before any weight loss occurs.
Cachexia is sometimes referred to as a paraneoplastic syndrome, which simply means symptoms that are caused by substances made by a cancer or by the body's reaction to cancer. It might seem like cachexia should be easily treated at first glance, but effective treatments are lacking. This is because cachexia is more than just a lack of calories in the body.
With regard to cancer, it is seen most frequently with lung cancer, pancreatic cancer, and stomach cancer. Cachexia not only worsens survival for people with cancer, but it interferes with quality of life. People with cachexia are less able to tolerate treatments, such as chemotherapy, and often have more side effects. For those who have surgery, postoperative complications are more common. Cachexia also worsens cancer fatigue, one of the most annoying symptoms of cancer.
Signs and Symptoms
The major symptoms of cachexia include:
- Involuntary (unintentional) weight loss -- Weight loss with cachexia is involuntary, meaning that it occurs without trying. Yet it goes further than unintentional weight loss. Weight loss may occur even though you are getting an adequate amount of calories in your diet, and if calorie intake outweighs output of energy.
- Skeletal muscle wasting -- Muscle wasting is a hallmark of cachexia and occurs along with loss of fat. It can also be fairly insidious. In people who are overweight at the time of their diagnosis, significant loss of muscle mass can occur without an obvious outward appearance of weight loss.
- Anorexia/loss of appetite -- Loss of appetite is another symptom of cachexia, and again, this symptom is somewhat different than ordinary "loss of appetite" symptoms. With cachexia, it is not simply a decreased desire for food, but more of a loss of a desire to eat.
- Lowered quality of life -- Muscle wasting can diminish your ability to walk and participate in activities that would ordinarily be enjoyable.
Taken from About Lung Cancer
Cachexia may be caused by "tumor factors" -- substances manufactured and secreted by a tumor, or by the "host response." Host response simply means the body's response to a tumor. The response of the immune system to cancer and other causes of cachexia is being studied to try and understand the underlying factors behind cachexia.
Cachexia is dominated by catabolic metabolism. If you think of normal metabolism being the building of tissue and muscle (anabolic metabolism), the opposite is true with cachexia, which is the breakdown of normal bodily processes.
There are several ways that cachexia can be evaluated. Some of these measures include:
- Body mass index (BMI) -- Body mass index describes not only relative body weight, but can give more information about a healthy weight. BMI is calculated using a formula of height and weight.
- Lean muscle mass -- Measuring body composition can help determine the ratio of lean muscle mass to body fat. Tests used to do this may include skin folds and bioimpedance.
- Food intake diaries -- Keeping a food diary is an important activity when looking to prevent or cope with cachexia. At the same time, it's important to keep in mind that the malnutrition of cachexia can occur even with an adequate intake of calories.
- Blood tests -- Some lab tests that are useful in evaluating cachexia include white blood cell counts (WBC), serum albumin, transferin levels, uric acid, and inflammatory markers, such as C-reactive protein (CRP).