151751-Najiba-Chargi

349 Systemic therapy: skeletal muscle mass and functional outcomes When adjusting for baseline characteristics in multivariable analyses, HPV status was not significantly associated with functional limitations, except for a smaller mouth opening at one-year post-treatment. Although no definite conclusions can be drawn, it seems that HPV status itself does not influence post-treatment functional limitations. Results in literature have contrasting results regarding the association of HPV status with functional limitations after RT (+). Vangelov et al. evaluated 100 patients with OPC treated with RT (+), and found that after adjusting for baseline characteristics (i.e., smoking, nodal stage, IMRT, and oropharyngeal RT dose), patients with an HPV positive tumor more often had tube feeding and weight loss, compared to patients with an HPV negative tumor. 44 Again, adjusted for baseline characteristics (i.e., age, gender, stage, treatment modality, RT dose, neck node irradiation, and pretreatment weight loss), Vatca et al., on the other hand, evaluat - ed 72 OPC patients treated with RT+ and found that patients with an HPV positive tumor had more mucositis and weight loss during treatment. 45 Sharma et al. evaluated 228 OPC patients and found that quality of life in HPV positive patients was lower shortly after treatment but became comparable by one year after treatment, also adjusted for baseline differences 46 , which is similar to our findings. A low skeletal muscle mass, or sarcopenia, before treatment, was associated with an impaired diet before and after treatment. This is in line with results of a previous study performed at our institute which demonstrated that sarcopenia is a strong determinant for feeding tube use after RT+ for head and neck cancer. 20 Skeletal muscle loss is thought to be related to swallowing muscle loss, causing swallowing difficulties whichmight result in a modified diet or eventually tube dependency. Moreover, swallowing problems itself may result in skeletal muscle loss due to insufficient nutritional intake. Therefore, these results support the hypothesis that sarcope - nia might be a relevant target to optimize patients’ condition before as well as after treatment to improve functional status. Apparently, our current preventive rehabilitation protocol does not target muscle mass sufficiently and/or not sufficiently long enough to close the gap be - tween sarcopenic and non-sarcopenic patients with regard to swallowing impairment. In view of the association between pretreatment sarcopenia and functional outcomes, integrating SMI determination before treatment is warranted. LIMITATIONS A limitation of this study is the suboptimal accrual during the first years of the data collection. These analyses were performed on data collected as part of standard care. Collecting data in this way usually introduced a risk for suboptimal inclusion especially during startup. Although at first inclusion rates were low, they improved over time with current inclusion rates between 79-85%, making it likely that this cohort is representative for the entire cohort. In addition, because baseline characteristics between included patients and not included patients were similar, no selection bias due to (non-)inclusion seems present. 17