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363 The elderly head and neck cancer patient: sarcopenia and survival INTRODUCTION Research into the field of body composition and specifically low skeletal muscle mass (SMM), sometimes also referred to as sarcopenia, has increasingly gained interest over the last decade in the field of oncology. In geriatrics, sarcopenia is known as an age-related syndrome with a multifactorial etiology, characterized by generalized loss of SMM and loss of muscle strength. 1 Risk factors for the presence of sarcopenia are malnutrition, immobilization and illness. Sar - copenia is a risk factor for various adverse outcomes including physical disability, decreased quality of life, and ultimately death. 1 In human aging, muscle wasting is an imminent process. It is estimated that the prevalence of sarcopenia in the general population is 5-13% for people aged 60-70 years, and up to 50% for those aged 80 years or above. 2 Independent of age, sarco- penia is impaired in various diseases due to inflammation, malnutrition and immobilization. Cachexia is a complexmetabolic syndrome inwhich inflammation is the key feature andweight loss (≥ 5% of body weight during the past 12 months) is the key diagnostic criterium. Cachexia can be an underlying condition in patients with sarcopenia. 3 The majority of research within the oncological community has defined sarcopenia as radio- logically assessed low SMM and/or low skeletal muscle quality. Previous research in elderly people showed that the correlation between SMM and muscle strength is moderate to weak and the relationship between muscle strength and SMM is not linear. 4,5 For this reason, the European working group on sarcopenia in older people (EWGSOP) recommended diagnosing sarcopenia based on the presence of both low SMM and low muscle function (MF; strength or performance). 1 Within the field of oncology, radiologically assessed low SMM appears to be a negative predic - tive and prognostic factor for various outcomes including disease progression and survival in a variety of cancer types. 6 For example, radiologically assessed low SMM is associated with chemotherapy dose-limiting toxicity in patients with head and neck cancer 7 , breast cancer 8 and renal cell carcinoma 9 ; increased incidence of postoperative complications in patients with head and neck cancer 10,11 , esophageal squamous cell carcinoma 12 and colorectal cancer 13 ; and decreased survival in patients with head and neck cancer 11,14 , colorectal cancer 15 and pancreatic adenocarcinoma 16 . In the majority of studies on the effect of sarcopenia on survival of cancer patients, and in all studies regarding head and neck cancer patients, only radiologically assessed low SMM was used to define sarcopenia. There are very few studies available in cancer patients that assess the prognostic value of sarcopenia as defined by the combination of low SMM and low MF. One study performed with gastric cancer patients who underwent gastrectomy showed that patients with sarcopenia, as defined by the combination of low SMM and lowMF, showed a significantly higher complication rate compared to patients without sarcopenia 17 . In head and neck cancer, no studies are available on the relationship between sarcopenia, as defined 18