151751-Najiba-Chargi

278 CHAPTER 15 as frequencies with corresponding percentages. Chi-square statistics were used for analyzing differences between the frequencies of each categorical variable with regard to the presence or absence of low SMM and of muscle changes. A Cox proportional hazard model was used for univariate and multivariate analysis of the predictors for loss of SMM (including patients from the groups of moderate and large loss of SMM) and for the prognostic impact of low SMM at baseline and a loss of SMM (including patients from the groups of moderate and large loss of SMM) after CRT on OS and DFS. The time interval chosen in the Cox proportional hazardmodel was the time between pre-CRT and follow-up imaging for estimating the predictors for loss of SMM and the time interval between diagnosis and the date of the event (death, recurrence) for estimating the prognostic impact of SMM on OS and DFS. Covariates used in the multivariate analysis were selected based on clinical relevance. Clinical relevance was determined based on literature and expert-opinion. Backward elimination was used to exclude potential predictors with a p-value of more than 0.05. Furthermore, the relationship between survival and SMM and change in SMM was visu - alized using Kaplan-Meier survival curves, including Log-rank tests. Statistical significance was evaluated at the 0.05 level using 2-tailed test RESULTS PATIENTS’ CHARACTERISTICS In total, 235 LA-HNC patients were identified who received cisplatin-based CRT between 2012 and 2018 and had evaluable pre-CRT and follow-up imaging of the head and neck area within 1 year. The median time between follow-up imaging and pre-CRT imaging was 6 months (IQR 5-9). The follow-up period of the included patients ranged fromNovember 2012 till May 2019. The clinical and demographic characteristics of the study population prior to initiation of CRT are presented in table 1. The majority of patients was male (70%). Mean age at diagnosis was 59 years (SD 8) and the mean body mass index (BMI) was 24.5 kg/m 2 . Nearly half of the patients (49%) had mild comorbidities as evaluated by the Adult Comorbidity Evaluation 27 (ACE-27) score. Most patients were current/former smokers (82%) and/or consumed alcohol (83%), 75% of patients had combined tobacco and alcohol use. Most patients had an Eastern Cooperative Oncology Group (ECOG) performance status of 1 (47%). The mean serum albumin levels of the included patients at diagnosis were 39.8 g/L (SD 4.6). Most patients had either a tumor located in the oral cavity (35%) or oropharynx (31%) of which the majority (60%) was not associated with human papillomavirus. A ma - jority of the patients (83%) was diagnosed with a tumor, node, metastasis (TNM) stage IV tumor and underwent CRT in a primary setting (71%).