151751-Najiba-Chargi

76 CHAPTER 5 ABSTRACT Background Low skeletal muscle mass is associated with adverse outcomes. For patients with head and neck cancer, skeletal muscle mass is often assessed at the third cervical vertebra (C3) on head and neck imaging. Various cut-off values for low skeletal muscle mass are proposed in literature. We aim to provide cut-off values for low skeletal muscle mass in head and neck cancer patients. Material and methods In total, 1415 patients with pre-treatment head and neck imaging between 2008 and 2018 were included. Skeletal muscle area was manually delineated at the level of C3 and corrected for patients squared height to obtain the cervical skeletal muscle mass index (CSMI). Gender and body-mass specific cut-off values for low skeletal muscle mass were calculated based on mean CSMI – 2 standard deviations (SD) as suggested by the European Working Group on Sarcopenia in Older People (EWGSOP). Results Of the 1415 included patients, the majority was male (69.8%) and had a body mass index (BMI) below 25 kg/m 2 (59.2%). A primary tumor localization in the oropharynx (35.3%) and a tumor, node, metastasis (TNM) stage IV tumor (60.5%) were most frequently observed. CSMI was significantly correlated with gender (r 2 =0.4, p<0.01) and BMI (r 2 =0.4, p<0.01). For male pa - tients with a BMI <25 kg/m 2 , a CSMI ≤6.8 cm 2 /m 2 was defined and with a BMI ≥25kg/m 2 a CSMI ≤8.5cm 2 /m 2 was defined for low SMM. For female patients with a BMI <25 kg/m 2 , a CSMI ≤5.3 cm 2 /m 2 was defined and with a BMI ≥25kg/m 2 a CSMI ≤6.4 cm 2 /m 2 was defined for low SMM. Conclusions This study is the first to provide standardized cut-off values for low SMM at the level of C3 in pa - tients with HNC. This information may aid in the uniformity of low SMM definition in research.