151751-Najiba-Chargi

295 Systemic therapy: skeletal muscle mass and oropharyngeal carcinoma INTRODUCTION Head and neck cancers (HNCs) are among the most frequent tumors in the world with an es - timated 835.000 new cases and 428.000 deaths in 2018. 1 The vast majority of HNCs are head and neck squamous cell carcinomas (HNSCCs), and most are related to alcohol consumption and/or smoking. 2, 3 There has been a rise in the incidence of HNSCC over the past decade, in particular, the incidence of oropharyngeal squamous cell carcinoma (OPSCC). This is largely due to a specific increase in incidence of a particular subset of OPSCC, which is driven by high- risk Human Papilloma Virus (HPV) infection. 4,5 In general, HPV-positive OPSCC has a better prognosis than HPV-negative OPSCC. 6 Other known prognostic factors in OPSCC include age, tumor stage, nodal stage, and comorbidities. 7, 8 For HPV-related OPSCC, several risk models have been published inmedical literature in order to gainmore precise prognostic information for this specific subset of HNSCCs patients, which may allow for development of treatment de-intensification approaches for HPV-associated OPSCC. 9-12 Ang et al. were the first to pro - pose a risk stratification model for OPSCC, which stratified patients according to HPV-sta - tus, smoking status, tumor and nodal stage into a low, intermediate and high risk of death. 9 Although previously reported risk models included a variety of known prognostic factors in OPSCC, none included body composition as a possible interacting variable. Over the last decade, the radiological assessment of individual body composition has increas - ingly gained interest in oncological patients. 13 Sarcopenia, sometimes also termed low skeletal muscle mass (SMM) or low lean body mass, is traditionally described as a geriatric syndrome consisting of both the specific loss of SMM and the decrease of skeletal muscle function. 14 Sarcopenia is a multifactorial syndrome; risk factors include malnutrition, immobility and illness. 14 In oncological studies, sarcopenia is often defined as low SMM only, because skeletal muscle function tests are not commonly performed in routine clinical practice. Sarcopenic obesity is described as the co-presence of both low SMM and obesity. 15,16 In several retrospective studies, low SMM and sarcopenic obesity have been associated with increased rates of postoperative complications, chemotherapy-related toxicity, and decreased survival rates in colon cancer, breast cancer, lung cancer, and pancreatic cancer, amongst others. 17,18,19 Research on the prevalence, predictive value and prognostic impact of low SMM and sarcopenic obesity in HNC patients has more recently been initiated. In patients with locally advanced HNSCC undergoing chemoradiotherapy, sarcopenia was associated with a trifold risk of chemotherapy dose-limiting toxicity. 20 Pre-treatment low SMM was associated with an increased incidence of pharyngocutaneous fistula and decreased overall survival in HNSCC patients undergoing a total laryngectomy. 21,22 A recent study in OPSCC patients showed an association between low SMM and decreased overall survival, independent of HPV-status. 23 In this study, only patients with advanced OPSCC were included and SMMwas assessed on a pre-treatment PET-CT scan of the abdomen. Even though measurement of SMM on a CT scan of the abdomen at the level of the third lumbar 16