Weight loss is a reduction in body mass characterized by a loss of adipose tissue (body fat) and skeletal muscle.
Description
Unintentional weight loss is the most common symptom of cancer and often a side effect of cancer treatments. A poor response to cancer treatments, reduced quality of life, and shorter survival time may result from substantial weight loss. The body may become weaker and less able to tolerate cancer therapies. As body weight decreases, body functionality declines and may lead to malnutrition, illness, infection, and perhaps death.
Most cancer patients in the United States expect to suffer weight loss during treatment for their disease; a study of 938 patients from 17 communities in upstate New York reported in 2004 that weight loss was the fourth most commonly expected side effect of cancer therapy, after fatigue, nausea, and sleep disturbances.
Severe malnutrition is typically defined in two ways: functionally (increased risk of morbidity and/or mortality) and by degree of weight loss (greater than 2% per week, 5% per month, 7.5% per 3 months, and 10% per 6 months). Without considering a specific time course, grading is as follows:
Grade 0 = less than 5.0% weight loss
Grade 1 = 5.0% to 9.9%
Grade 2 = 10.0% to 19.9%
Grade 3 = greater than 20.0%
Grade 4 (life-threatening) is not specifically defined. Paying attention to weight loss at an early stage is necessary to prevent deterioration of weight, body composition, and performance status.
Causes
There are many reasons for weight loss in cancer patients, including appetite loss because of the effect of cancer treatments (chemotherapy, radiation therapy, or biological therapy) or psychological factors such as depression. Patients may suffer from anorexia and lose desire to eat, and thus consume less energy. When inadequate calories are consumed, it can lead to "wasting" of body stores (muscle and adipose tissue). Weight loss may be temporary or may continue at a life-threatening pace.
Weight loss may be also be a consequence of an increased requirement for calories (energy) due to infection, fever, or the effects of the tumor or cancer treatments. If infection or fever is present, it is necessary to consider that there is an increased caloric need of approximately 10% to 13% per degree above 98.6°F (37°C). Therefore, energy intake has to be increased to account for this rise in body temperature.
Weight loss may be a result of a common problem in cancer called cachexia. Approximately half of all cancer patients experience cachexia, a wasting syndrome that induces metabolic changes leading to a loss of muscle and fat. It has been proposed that cachexia may be due to the effects of the tumor, but this is debatable considering some patients with very large tumors do not experience cachexia, while others do even though tumors are less than 0.01% of body mass. Cachexia is most common in patients with pancreatic and gastric cancer. Approximately 83% to 87% of these patients experience weight loss. Cachexia is characterized by such symptoms as decreased appetite, fatigue, and poor performance status. It can occur in individuals who consume enough food, but due to disease complications, cannot absorb enough nutrients (i.e. fat malabsorption). Although energy expenditure is sometimes increased, cachexia can occur even with normal energy expenditure. Cachexia is multifactorial in nature and associated with mechanical factors, psychological factors, changes in taste, and cytokines. It should be distinguished from anorexia, in which there is a loss of desire to eat, resulting in weight loss. Cachexia is a serious complication in cancer patients, thought to be responsible for as many as 20% of all deaths from cancer.
Special Concerns
In order to allow normal tissue repair following aggressive cancer therapies, patients require adequate calories and macronutrients in the form of protein, carbohydrates, and fat. Inadequate consumption of food and/or poor nutrition may impair the ability of a patient to tolerate a specific therapy. If a low tolerance to therapy necessitates a decrease in dose, the therapy's effectiveness could be compromised. Wound healing may also be impaired with poor nutrition and inadequate energy intake.
Research has demonstrated that men often experience significantly more weight loss than women over the course of the disease and lose weight much faster. On average, survival time for men is shorter than for women. Significant predictors of patient survival are stage of disease, initial weight-loss rate, and gender.
Treatments
Nutritional problems related to side effects should be addressed to ensure adequate nutrition and prevent weight loss. In particular, cancer patients should maintain an adequate intake of calories and protein to prevent protein-calorie malnutrition. The patient's caloric requirements can be calculated by a dietitian or doctor since nutrient requirements vary considerably from patient to patient. Moreover, patient education about nutrition is vitally important; several recent studies have shown that almost half of all cancer patients in the United States receive no nutritional information from health care professionals, including the 18% who experience significant weight loss.
The following dietary tips may help patients to reduce weight loss:
Eat more when feeling the hungriest.
Eat foods that are enjoyed the most.
Eat several small meals and snacks instead of three large meals. A regular meal schedule should be kept so meals are not missed.
Have ready-to-eat snacks on hand such as cheese and crackers, granola bars, muffins, nuts and seeds, canned puddings, ice cream, yogurt, and hard boiled eggs.
Eat high-calorie foods and high-protein foods.
Take a small meal as to enjoy the satisfaction of finishing a meal. Have seconds if still hungry.
Eat in a pleasant atmosphere with family and friends if desired.
Make sure to consume at least eight to 10 glasses of water per day to maintain fluid balance.
Consider commercial liquid meal replacements such as Ensure, Boost, Carnation, and Sustacal.
An appetite stimulant may be given in order to prevent further weight loss such as megestrol acetate or dexamethasone.In clinical trials, both these medications appear to have similar and effective appetite stimulating effects with megestrol acetate having a slightly better toxicity profile. Fluoxymesterone has shown inferior efficacy and an unfavorable toxicity profile.
As of 2004, researchers at the Medical College of Virginia are studying a group of compounds known as cannabinoids for the treatment of cachexia and vomiting associated with cancer treatment. The best-known natural cannabinoids are derived from marijuana.
Further research is needed in order to devise an effective treatment for the loss of muscle tissue in cachexia. As of 2004, there are no medications, nutritional supplements, or other treatments that are even moderately successful in reversing the wasting of muscle tissue in cachexia.
Alternative and Complementary Therapies
Depression may affect approximately 15%–25% of cancer patients, particularly if the prognosis for recovery is poor. If anorexia is due to depression, there are antidepressant choices available through a physician. Counseling may be also be sought through a psychologist or psychiatrist to cope with depression.
It is important to check with a dietitian or doctor before taking nutritional supplements or alternative therapies because they may interfere with cancer medications or treatments. St. John's Wort has been used as a herbal remedy for treatment of depression, but it and prescription antidepressants is a dangerous combination that may cause symptoms such as nausea, weakness, and may cause one to become incoherent.
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