Frailty, sarcopenia, cachexia and malnutrition are a group of vulnerabilities said to be endemic in patients with advanced cancer. All are associated with poor outcomes, including patient quality of life, complications of cancer surgery, severe toxicity of systemic therapies and mortality. It remains unclear how to diagnose these different conditions and to weigh cancer treatment options in the light of these vulnerabilities and difficult to assess in what extent and by what means they are preventable or reversible. Definitive diagnostic criteria have not yet been developed for frailty, sarcopenia, cachexia and malnutrition in a clinical oncology setting. However existing conceptual frameworks for these entities overlap considerably, all sharing core domains of reduced physical functioning, body depletion of overall weight, fat and skeletal muscle mass, and tumor-driven systemic alterations that may be metabolic, inflammatory, neural, endocrine or other. Assessment of these dimensions provides valuable information concerning prognosis and can inform risk assessment in relation to likelihood of complication / toxicity. Options for clinical management of frailty, sarcopenia, cachexia and malnutrition are limited, however the wasting process can be contained to some degree. Reduced dietary intake is a key driver of weight loss and muscle depletion, and this can be mitigated to varying degrees by meticulous pain and symptom management, consultation with a nutrition health care professional, specially formulated medical foods, and drug therapy to restore appetite.