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394 CHAPTER 19 ing incorporating skeletal muscle mass into clinical practice in real-time. It is expected that automated methods, e.g., automated computed tomography segmentation, will accelerate body composition research and, eventually, facilitate the integration of body composition measures into clinical care. 22 The interest in the role of sarcopenia in oncology has been increasing over the past decade. Several articles exhibit the negative impact of sarcopenia on adverse health outcomes. 23 Frailty is also related to adverse health outcomes[9]. Sarcopenia and frailty are linked to each other, even though the treatments and suggested underlying concepts differ. Treatment of sarcope - nia is focused on combining exercise and adequate protein intake to increasing muscle mass and strength, while frailty is focused on a broader set of physical and non-physical domains. 24 Thereby several definitions of frailty are in use, depending on how frailty is measured. 25 The majority of frailty tools have been based upon one of two concepts of frailty: physical phe- notype (Fried) or the multiple deficit model (Rockwood). 26,27 Additionally, several definitions of sarcopenia are used i.e., the EWGSOP- or IWGS-criteria. 28 But more recent proposals for the definition of sarcopenia include muscle function in addition to muscle mass. 13,29 Studies using a physical definition of frailty tend to show more similarities with sarcopenia. 1230 So, both the concepts of frailty and sarcopenia are evolving, and there is still no full consensus on which to use in clinical practice. It is also important that frailty screening tools should be used to determine which patients should benefit from a CGA; not to diagnose frailty. The CGA is the current gold standard test for defining frailty. The G8 frailty screening questionnaire has insufficient discriminative power 10 , and it is not yet known if assessment of skeletal muscle mass is suitable for screening of patients who need to undergo a CGA 10 . This needs to be investigated by comparing skeletal muscle mass with the CGA. Research in muscle density is another interesting field, as recently, muscle density on CT imaging was reported to be more associated with frailty than muscle mass. 31 As mentioned before, previous studies indicate that sarcopenia, based on loss of skeletal musclemass, occurs in 35.5–54.5%of the patients with HNC. 32,33 In our cohort, sarcopenia was based on a combination of handgrip strength and at CT/MRI measured skeletal muscle mass. Using those two factors the prevalence of sarcopenia in our cohort was only 14 %, likely due to the small prevalence of low handgrip strength. Reiss et al reported on the consequences of applying the new EWGSOP2 guideline instead of the former EWGSOP1 guideline for sarcopenia diagnosis in older adults and expressed their concerns regarding missing sarcopenic patients due to the novel EWGSOP definition in which lower cut-off values for handgrip strength mea - surements are used. 34 Our study has limitations. The use of two different imaging techniques may raise concerns. Either CT or MRI imaging were used for the assessment of skeletal muscle mass, to maximize the number of patients that could be included. But recent research shows that these two different imaging modalities show significant correlation in quantifying skeletal muscle mass