151751-Najiba-Chargi

54 CHAPTER 4 ABSTRACT Background Patients with head and neck cancer (HNC) are at increased risk of developing low skeletal muscle mass (sarcopenia), which is associated with adverse treatment outcomes and progno - sis. Sarcopenia is most commonly assessed by the skeletal muscle cross sectional area (CSA) at the third lumbar vertebra (L3) or more recently the third cervical vertebra (C3). L3 is not routinely imaged and C3may be impacted by disease or treatment. As alternative we analyzed masseter muscle characteristics and their relationship with L3 and C3 skeletal muscle CSA and overall survival. Methods In this single-center retrospective study, 113 patients with HNC who underwent whole body FDG-PET/CT-scans were reviewed. Of these patients, L3 CSA, C3 CSA, masseter CSA, masseter thickness, masseter volume, masseter Hounsfield Unit values, lumbar skeletal muscle mass index (LMSI), cervical skeletal muscle mass index (CSMI) and masseter skeletal muscle mass index (MSI) were recorded and correlated with each other and with overall survival. Results We included 81 male and 32 female patients. The masseter muscle parameters differed signifi - cantly between sexes. The Spearman correlation coefficients between C3 CSA and Masseter volume and between L3 CSA ad Masseter volume were 0.67 and 0.54 (p < 0.001) respectively. In multivariate analysis, low MSI was a significant predictor for decreased overall survival (HR 3.0, p<0.01). Conclusion There is a strong association between masseter muscle volume and C3 CSA and L3 CSA. Low SMM (MSI) predicts decreased overall survival. Further research should investigate the rela - tionship between muscle function and masseter muscle parameters and impacting factors on masseter muscle dimensions.