Cancer-related anorexia (loss of appetite) and cachexia (a complex wasting syndrome) are common and distressing problems for many patients. Cachexia is characterized by involuntary loss of muscle mass and fat that often cannot be reversed by simple nutritional support alone. This profound weight loss is associated with a poorer quality of life, reduced tolerance for cancer treatments, and diminished overall survival. Managing appetite is a priority to help patients maintain strength, better endure therapy, and improve well-being. Medical professionals address this using established medications, newer pharmaceutical options, and practical dietary changes.
Primary Pharmacological Appetite Stimulants
The most widely used class of drugs for stimulating appetite in cancer patients are the progestins, with megestrol acetate being the most common agent. This synthetic version of progesterone is believed to enhance appetite by modulating neurotransmitters and reducing inflammatory cytokines. Megestrol acetate has been shown to significantly increase appetite and promote weight gain in many patients.
The primary drawback to using progestins is the side effect profile, which includes a higher risk of thromboembolism (blood clots) and fluid retention. Other possible effects include high blood pressure and elevated blood sugar levels. As a hormonal agent, megestrol acetate can also cause changes like hot flashes and a rounded facial appearance.
Corticosteroids, such as dexamethasone or prednisone, are another established class of agents used to stimulate appetite. They are thought to work by mimicking natural adrenal hormones, improving appetite partly due to their anti-inflammatory properties and a general sense of improved well-being. They are often favored for their rapid onset of action, sometimes showing improvement within days.
A significant limitation of corticosteroids is their unsuitability for long-term use due to extensive side effects. Prolonged use can lead to muscle weakness (myopathy), increased risk of infection, and metabolic changes like elevated blood sugar. Mood changes, including euphoria or insomnia, are also common. These long-term health risks often restrict their use to patients with a shorter life expectancy.
Secondary and Emerging Pharmaceutical Options
When primary agents are unsuitable or fail to provide relief, other medications are considered, including cannabinoids like dronabinol. Dronabinol is a synthetic form of delta-9-tetrahydrocannabinol (\(\Delta^9\)-THC). It primarily stimulates appetite by activating the Cannabinoid-1 (CB1) receptors in the brain, which regulate hunger.
Dronabinol is often chosen for patients also experiencing significant nausea and vomiting related to chemotherapy, as it has anti-nausea effects. However, its use is associated with central nervous system side effects, such as dizziness, confusion, drowsiness, and altered thinking. These cognitive effects, along with potential heart rate and blood pressure changes, necessitate careful monitoring.
A newer class of medication involves ghrelin agonists, like anamorelin, which target the body’s natural “hunger hormone” pathway. Ghrelin stimulates appetite and promotes the release of growth hormone, which helps build muscle mass. Anamorelin mimics ghrelin, aiming to increase both appetite and lean body mass, though its effect on physical function remains inconsistent across studies.
Ghrelin agonists are a developing area of therapy; anamorelin is currently available in some countries for cancer cachexia. Possible side effects include metabolic issues such as hyperglycemia and diabetes. Other agents, such as the anti-nausea drug metoclopramide, may be used off-label to address early satiety by helping the stomach empty more quickly.
Non-Pharmacological and Dietary Strategies
Addressing appetite loss often begins with simple, practical changes to eating habits and the meal environment. Patients benefit significantly from shifting away from traditional three large meals a day to eating smaller, more frequent portions. This strategy prevents the overwhelming feeling of fullness or early satiety that often accompanies cancer-related appetite loss.
Focusing on the nutritional density of food is particularly important when intake volume is limited. This means maximizing calories and protein in every bite without increasing the physical size of the meal. Simple additions like butter, healthy oils, cheeses, powdered milk, or nut butters can significantly fortify meals. Liquid nutritional supplements, consumed in small amounts throughout the day, also provide substantial calories and protein.
Behavioral modifications further support increased food intake by making the eating experience more pleasant. It is helpful to limit drinking large quantities of liquids during meals, as this can fill the stomach prematurely and reduce caloric intake. Creating a calm, pleasant atmosphere with soft music or attractive place settings can encourage eating. Since patients often have a better appetite in the morning, taking advantage of these times to consume the most nutrient-dense foods is recommended.
Light physical activity, if medically approved, plays a supportive role in managing appetite and combating muscle loss. Regular, gentle exercise has been shown to help stimulate a natural desire to eat and maintain muscle mass.
Selecting the Right Treatment
Selecting the most appropriate appetite stimulant is an individualized decision based on the patient’s overall clinical situation. The choice is determined by factors such as the patient’s prognosis, the specific type of cancer, and existing health conditions. For instance, a patient with a history of blood clots would likely be advised against megestrol acetate due to its increased risk of thromboembolism.
A significant consideration is the trade-off between a drug’s efficacy and its side effect profile. Corticosteroids offer rapid appetite improvement, but their short-term use is preferred due to the risk of long-term complications like bone weakness and metabolic changes. In contrast, progestins like megestrol acetate are often chosen for patients needing a more sustained appetite boost over months, provided they can tolerate the risks.
The overall goals of care heavily influence the treatment decision, particularly distinguishing between curative and palliative intent. For patients with advanced disease and a short life expectancy, the goal shifts toward comfort and rapid symptom relief. This makes a short course of a corticosteroid, for its immediate euphoric and appetite-enhancing effect, a reasonable choice. Conversely, if the patient has a longer projected survival, the focus is on a sustainable option that promotes weight maintenance with a manageable side-effect profile.