151751-Najiba-Chargi

182 CHAPTER 10 Therefore, the aim of the current study was to investigate the predictive impact of low SMM for cisplatin DLT in a 10-year cohort of patients with LA-HNC treated with cisplatin-based chemoradiotherapy. MATERIAL AND METHODS STUDY DESIGN A retrospective study was conducted in which all patients who were diagnosed with LA-HNC and treated in the UMC Utrecht with cisplatin-based chemoradiotherapy between 2007 and 2018 were screened for inclusion. Inclusion criteria for this study required that patients were treated with curative intent in primary or adjuvant setting and had pre-treatment imaging of the head and neck area within 1 month before the start of chemoradiotherapy and had data available on cisplatin dosages and reported toxicities. Relevant demographic, clinical, biochemical and anthropometric variables were retrieved from electronic medical records. This study also included the patients who were treated with cisplatin from our previous study. 8 ETHICAL APPROVAL The design of this study was approved by the Medical Ethical Research Committee (METC) of the University Medical Center Utrecht, METC ID: 17-365/C. The requirement for informed consent from patients was waived because of its retrospective design. THERAPY Chemotherapy regimen consisted of three cycles of intravenous cisplatin-based chemother- apy on days 1, 22 and 43 of treatment. Cisplatin dose was 100 mg per m 2 of body surface area. Chemoradiotherapy was given in primary setting for patients with (technical or functional) irresectable LA-HNC and in postoperative setting for tumors with their aforementioned high- risk features. Radiotherapy was administered in 35 fractions of 2 Gy to a total dose of 70 Gy (primary setting) or in 33 fractions of 2 Gy to a total dose of 66 Gy (postoperative setting). BODY COMPOSITION MEASUREMENTS- SKELETAL MUSCLE MASS AND LEAN BODY MASS SMMwas segmented as skeletal muscle area using the Slice-O-matic software (version 5.0). At the level of the third cervical vertebrae (C3), a single slice was used for skeletal muscle area seg - mentation. The first slide to completely show the entire vertebral arc when scrolling through the C3 vertebra fromcaudal to cephalic directionwas selected. For computed tomography (CT) imaging, muscle area was defined as the pixel area between the radiodensity range of -29 and +150 hounsfield units, which is specific for muscle tissue. 14 For magnetic resonance imaging (MRI), muscle area was manually segmented, and fatty tissue was manually excluded. Because the overall intraclass correlation coefficient for the skeletal muscle area obtained by CT and