151751-Najiba-Chargi

307 Systemic therapy: skeletal muscle mass and oropharyngeal carcinoma turned by improving a patient’s physical condition and nutritional status before and during treatment. Future research is needed to clarify these mechanisms. Treatment strategies may be personalized to the patient’s specific body composition to decrease the risk of severe tox - icity and adverse outcomes, while still maintaining optimal efficacy. A limitation of this study is the retrospective design which increases the risk of systemic errors andmissing data. For example, HPV-status was not available in all patients in this cohort; thus, for survival analysis, patients without a known HPV-status were excluded. Another limitation is that low SMMwas not defined according to sex-specific cut-offs, whichmay result in an over - representation of women in the low SMM group. When more data of female HNSCC patients is available, we aim to define sex-specific cut-offs for low SMM in HNSCC patients. Another limitation is that survival was not measured by treatment modality due to heterogeneity and variations between- andwithin treatment modalities. Further research is needed to investigate the role of low SMM on survival in patients treated with different treatment modalities. Our recently publishedmeasurement method for SMM at the level of C3 allows for the routine eval- uation of sarcopenia in almost all head and neck cancer patients. In the future, this tool may be used as a screening tool for patients at risk of severe toxicity or complications from treatment. This study has examined the prevalence and prognostic value of low SMM and sarcopenic obesity, while adjusting for a variety of known confounders (e.g., comorbidity, weight loss, BMI, HPV-status, TNM-stage), in a large cohort of OPSCC patients. The findings in this study highlight the potential usefulness of determining pre-treatment SMM in HNC patients and contributes to a growing knowledge of low SMM and sarcopenic obesity in HNSCC patients. This knowledge can be used for the development of new interventions, patient management and treatment decisionmaking. In addition, this information can be used for the development of improved risk stratification models in OPSCC patients and de-intensification approaches in HPV-related OPSCC. CONCLUSION Pre-treatment low skeletal muscle mass is highly prevalent in patients with oropharyngeal squamous cell carcinoma. The simultaneous presence of low skeletal musclemass and obesity, sarcopenic obesity, has a statistically significant association with decreased overall and dis- ease-free survival, independent fromother well-known prognostic factors such as HPV-status. Therefore, skeletal muscle mass should be considered as a pre-treatment prognostic factor in clinical decision making. 16