Sarcopenia, which is defined as a decrease in skeletal muscle mass and strength with aging, is an important risk factor in clinical medicine that is associated with mortality, and poor surgical and nonsurgical outcomes. Sarcopenia is now recognized as a multifactorial geriatric syndrome. Cachexia is defined as a metabolic syndrome with inflammation as the key feature, so cachexia can be an underlying condition of sarcopenia. Recently, cachexia has been defined as a complex metabolic syndrome associated with an underlying illness and characterized by the loss of muscle mass with or without a loss of fat mass. These two conditions overlap but are not the same. In clinical practice, many factors related to sarcopenia (decreased food intake, inactivity, and decreased hormones) are reported frequently in patients with cachexia. On the contrary, systemic inflammation, the core feature of cachexia, can also be present in apparently healthy older sarcopenic patients. This suggests that new therapeutic approaches, alone or in combination, may be appropriate in both conditions.

Nutritional deficiency after gastrectomy is caused by anatomical and physiologic changes in the stomach. In the case of patients with gastric cancer, nausea and loss of appetite due to cancer cachexia syndrome can affect nutritional status after gastrectomy. Prognostic nutritional index based on preoperative nutritional conditions is used for prediction of postoperative outcomes including long-term survival. Generally, enteral nutrition is more effective for post-gastrectomy conditions than parenteral nutrition. In addition, specialized enteral formulas such as immunonutrition (amino acids, ω-3 fatty acids and nucleotide) seem to have benefits for gastrectomy patients, although there is still insufficient evidence. Ghrelin is a next generation agent to stimulate appetite in patients that underwent gastrectomy.

Cancer-related anorexia-cachexia syndrome (CACS) is a hypercatabolic state, characterized by reduced appetite and weight loss due to ongoing loss of skeletal muscle mass and adipose tissue. CACS occurs mainly in patients with advanced cancer; thus, weight loss in CACS is often associated with poor prognosis and decreased survival. A large number of studies have been conducted on various pharmacologic agents for palliation of cancer-related anorexia. The purpose of this article is to review the pre-existing pharmacologic agents used for CACS and to evaluate the evidence from current studies on each pharmacologic agent. First, appetite stimulants such as corticosteroids, progestins, cyproheptadine, and cannabinoid have been shown to be beneficial by improving appetite and helping with weight changes even if they had no effect on survival rate. Several other agents with anti-inflammatory effects (e.g., eicosapentaenoic acid, thalidomide, and melatonin), prokinetic agents (e.g., metoclopramide), anabolic agents (e.g., androgens and growth hormone), antipsychotics (e.g., mirtazapine and olanzapine), and antiemetics have also been studied in patients in CACS; however further investigations would be required to confirm the beneficial effects.