151751-Najiba-Chargi

19 Introduction AIM AND OUTLINE OF THIS THESIS The introduction describes the poor prognosis of patients with HNSCC and in particular of patients with locally advanced HNSCC. Besides the poor prognosis, treatment of HNSCCC is also associated with a high frequency of severe toxicities. Over the past decade, research on body composition cancer is rapidly increasing. Themain of the research described in this thesis is to evaluate diagnostic measurements of skeletal muscle mass, to evaluate the predictive and prognostic value of low skeletal muscle mass in patients with HNSCC who are surgically treated and who are treated with systemic therapy (chemoradiotherapy and bioradiotherapy). Part I of this thesis presents the diagnostic research on skeletal muscle mass measurements. Before investigating the predictive and prognostic value of skeletal musclemass themeasure- ment method has to be validated and its robustness tested. Therefore, in Chapter 2 we correlate skeletal muscle mass measurement on head and neck computed tomography imaging at the level of the third cervical vertebra and on abdominal im- aging at the level of the third lumbar vertebra in a large cohort of patients. Because sometime only MRI of the head and neck is available and CT not, we correlate in Chapter 3 measurement of skeletal musclemass at the level of the third cervical vertebrae using computed tomography imaging and magnetic resonance imaging. In an attempt to find an alternative skeletal mass measurement on head and neck CT, we investigate the association of muscle segmentation of the musculus masseter and muscle segmentation at the level of the third cervical and lumbar vertebra in Chapter 4 . Because gender specific cut-off values for defining low skeletal muscle mass on head and neck are missing, we developed new cut-off values for low skeletal muscle mass obtained by image-analysis in patients with head and neck cancer in Chapter 5 . Part II of this thesis presents the predictive and prognostic impact of skeletal muscle mass in surgically treated head and neck cancer patients. The predictive and prognostic value of skeletal muscle mass may differ for specific head and neck cancer patient groups. Thereore, groups of head and neck cancer patient undergoing surgical procedures with high and low risk of complications are investigated. In Chapter 6 we investigated the predictive and prognostic impact of low skeletal muscle mass on postoperative morbidity and survival in oral cavity cancer patients undergoing surgical resection and mandibular microvascular reconstruction with a free fibula flap. Besides skeletal musclemass, systemic inflammationmay also influence treatment outcomes of head and neck cancer patients undergoing microvascular free flap re- construction. Therefore, in Chapter 7 we investigated the predictive and prognostic impact of low skeletal musclemass and elevated systemic inflammation on postoperativemorbidity and survival in head and neck cancer patients undergoing microvascular free flap reconstruction using a variety of free flaps. The predictive impact of skeletal muscle mass on perioperative complications is further investigated in patients with oral squamous cell carcinoma and pre- sented in Chapter 8 . Besides skeletal muscle mass, arterial calcification is also assessed on routine diagnostic CT imaging and could be used as an additional image-based biomarker. 1