Appetite loss and cancer
Appetite loss, medically termed anorexia, is a common issue faced by cancer patients, affecting approximately 15 to 25 percent of individuals diagnosed with cancer, and rising to as high as 90 percent in those with advanced stages of the disease. This loss of appetite can stem from the cancer itself or the treatments administered, such as chemotherapy, which can cause alterations in taste, mouth sores, dry mouth, and gastrointestinal issues that diminish the desire to eat. Emotional factors, including fear and depression, as well as psychological reactions to treatment side effects, further exacerbate this condition.
Biologically, cytokines produced by tumor cells can influence the central nervous system and gastrointestinal tract, promoting appetite loss. The impact of appetite loss is significant, often leading to weight loss and a poorer quality of life, and it is particularly prevalent in patients with lung, stomach, pancreas, or esophagus cancers. Various strategies exist to manage appetite loss, ranging from dietary adjustments, like liquid meal replacements and smaller meal portions, to medications designed to stimulate appetite or inhibit appetite-decreasing factors. While appetite loss may resolve when the underlying cause is addressed, it can be associated with cachexia, a syndrome that significantly worsens the patient's condition and is linked to higher mortality rates in advanced cancer cases.
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Appetite loss and cancer
ALSO KNOWN AS: Anorexia
RELATED CONDITIONS: Cachexia
DEFINITION: Loss of appetite in cancer patients, referred to by medical professionals as anorexia, may result from either the cancer itself or the treatments used to combat the disease. Cancer-related anorexia is associated with weight loss and has been shown to correlate with a poorer outcome and a lower quality of life.
Risk factors: Those with cancer and undergoing chemotherapy for cancer are at risk.
Etiology and the disease process: Because many cancer treatments affect not only cancer cells but also healthy cells, several unwanted side effects may result. For instance, chemotherapy may reduce the turnover of taste receptor cells in the tongue, which may alter the flavor of food. Additional damage to other cell types in the mouth may result in sores, gum disease, dry mouth, and sore throat. Cells in the digestive tract may also be injured, resulting in abnormal gut motility and difficulty swallowing. Together, these effects may change the way food tastes and decrease the desire to eat.
Emotional side effects, such as fear and depression, as well as psychological effects, such as the development of taste aversions due to the nauseating side effects of chemotherapy, can also contribute to the loss of appetite. Furthermore, many cancer patients with anorexia report early satiety, meaning that they feel full after eating only a small amount of food.
Biological causes for cancer-related anorexia also exist. Cytokines released by tumor cells or produced by immune cells in response to cancer may affect the central nervous system and the gastrointestinal tract to promote appetite loss. Specifically, the central nervous system is responsible for controlling food intake and energy homeostasis, while effects on the gastrointestinal tract can influence feelings of fullness. Examples of cytokines that may affect appetite include tumor necrosis factor-alpha (TNF-α), C-reactive protein, interleukin-1 beta (IL-1 beta), IL-6, and tumor-derived lipid mobilizing factor (LMF). However, there is some conflicting data as to whether blood levels of these cytokines correlate with, or are responsible for, the loss of appetite.
Incidence: In general, approximately 15 to 25 percent of cancer patients report loss of appetite. The incidence can be as high as 90 percent for patients with advanced cancers. However, different types of cancers tend to have different rates of anorexia. For example, a large percent of patients with cancers of the lung, stomach, pancreas, or esophagus has significant weight loss caused, in part, by anorexia. However, loss of appetite is not as frequent in patients with breast or prostate cancer.
Treatment and therapy: Cancer-related anorexia may be managed by either changing eating habits or taking medication. There are several dietary suggestions for cancer patients who struggle with loss of appetite. Liquid or powdered meal replacements, juice, soups, and milk-based drinks or shakes may be used in place of solid food to provide nutrients. Eating several small meals or snacks instead of three large meals per day may also be more feasible for patients with cancer-related anorexia. Additionally, drinking a glass of wine or exercising regularly may also stimulate the appetite. However, patients should consult with their doctors before consuming alcohol or beginning an exercise regimen.
The pharmacological treatment of cancer-related anorexia can be broadly divided into three groups: appetite stimulants, anticatabolic agents, and anabolic agents.
Examples of appetite stimulants include progestational agents (such as megestrol acetate and medroxyprogesterone), which can improve caloric intake. Corticosteroids (such as prednisolone and methylprednisolone) may improve appetite because of their inhibition of prostaglandin metabolism and IL-1 signaling. Cyproheptadine, an antihistamine, is also a serotonin antagonist, and its effects on this neurotransmitter in the brain can also promote an increase in appetite. Cannabis (marijuana) can stimulate CB1 receptors in the brain to enhance appetite, and it can also reduce nausea and cancer pain. Although cannabis was controversial in the past, its increased legalization in states throughout the United States, has brought it into the mainstream.
Anticatabolic agents, which inhibit the production or activity of appetite-decreasing cytokines, are also important in combating cancer-related anorexia. Examples include thalidomide (a potent inhibitor of TNF-α production) and eicosapentaenoic acid (an inhibitor of adenylate cyclase activity and tumor-derived LMF activity).
Anabolic agents such as oxandrolone and fluoxymesterone have been studied as well, and they may build lean tissue mass by increasing muscle protein synthesis. The hormone androgen may also be useful in cancer patients (except for those with hormone-dependent tumors) as it can promote muscle growth and strength and may also induce the secretion of leptin, a hormone produced by adipose tissue to stimulate appetite.
In the 2020s, several new medications showed promise in increasing the appetites of cancer patients. Anamorelin, a ghrelin receptor, and L-carnitine both showed promise in clinical trials. Enobosarm, a selective androgen receptor modulator, helped patients increase muscle mass. Thalidomide and Lenalidomide, as well as fish oil, also became common for their anti-inflammatory properties.
Prognosis, prevention, and outcomes: Generally, appetite loss resolves itself when its underlying cause is remedied. Although appetite loss can interfere with the healing process, it does not usually increase mortality in patients with early-stage cancers. However, cancer-related anorexia is often associated with cachexia, a wasting syndrome characterized by not only the loss of appetite but also weight loss, breakdown of muscle tissue, depletion of reserves within fat (adipose) tissue, fatigue, and weakness. In advanced-stage cancer, the cancer anorexia-cachexia syndrome is observed in about 80 percent of patients and is one of the most frequent causes of death.
Bibliography
Behl, D., and A. Jatoi. “Pharmacological Options for Advanced Cancer Patients with Loss of Appetite and Weight.” Expert Opinion on Pharmacotherapy, vol. 8.8, 2007, pp. 1085–90.
Chi, Kwan-Hwa, et al. "MS-20, a Chemotherapeutical Adjuvant, Reduces Chemo-Associated Fatigue and Appetite Loss in Cancer Patients." Nutrition and Cancer, vol. 66.7, 2014, pp. 1211–19.
Cleeland, Charles S., Michael J. Fisch, and Adrian J. Dunn, eds. Cancer Symptom Science: Measurement, Mechanisms, and Management. Cambridge: Cambridge UP, 2011.
Ginn, Edward H., ed. Coping with Cancer: Pain Control and Eating Suggestions. New York: Nova Biomedical, 2014.
Perboni, S., and A. Inui. “Anorexia in Cancer: Role of Feeding-Regulatory Peptides.” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 361.1471, 2006, pp. 1281–89.
Poole, K., and K. Froggatt. “Loss of Weight and Loss of Appetite in Advanced Cancer: A Problem for the Patient, the Carer, or the Health Professional?” Palliative Medicine, vol. 16.6, 2002, pp. 499–506.
Rubin, H. “Cancer Cachexia: Its Correlations and Causes.” Proceedings of the National Academy of Sciences of the United States of America, vol. 100.9, 2003, pp. 5384–89.
Solheim, Tora S., et al. "Weight Loss, Appetite Loss, and Food Intake in Cancer Patients with Cancer Cachexia: Three Peas in a Pods?—Analysis from a Multicenter Cross-Sectional Study." Acta Oncologica, vol. 53.4, 2014, pp. 539–46.
Takahashi, Shunji et al. “The Incidence and Management of Cancer-Related Anorexia During Treatment with Vascular Endothelial Growth Factor Receptor-Tyrosine Kinase Inhibitors.” Cancer Management and Research, vol. 15 1033-1046, 22 Sept. 2023, doi:10.2147/CMAR.S417238doi.org/10.2147/CMAR.S417238.