PD-0774 Impact of sarcopenia on acute radiotherapy-induced toxicity in head and neck cancer patients

Purpose or Objective: Sarcopenia, i.e. generalised and progressive loss of skeletal muscle mass and muscle function, is related to more late radiation-induced toxicities and worse survival in head and neck squamous cell carcinoma (HNSCC) patients. The objective of this study was to test the hypothesis that sarcopenia improves the performance of NTCP models to predict acute toxicity in HNSCC patients treated with definitive radiotherapy (RT). Materials and Methods: This was a retrospective analysis in a prospective cohort of HNSCC patients treated from January 2007 to December 2018 with RT with or without systemic therapy. Physician- and patient-rated toxicities, including dysphagia, xerostomia, sticky saliva, aspiration, oral mucositis, weight loss and fatigue, were collected prospectively during (week 1-7) and after treatment (week 12, month 6-24. Planning CT-scans were used for evaluating patients’ skeletal muscle mass at the third cervical vertebra for estimation of the skeletal muscle index (SMI). Chi-square and t-tests were used to compare the characteristics and baseline toxicities of sarcopenic and non-sarcopenic patients. The linear predictors for each endpoint from three to seven weeks during treatment were calculated based on the NTCP models developed at our department. The impact of sarcopenia was analysed using multivariable logistic regression analyses. If sarcopenia remained significant next to the linear predictor, likelihood-ratio tests were performed to test whether the model including sarcopenia performed significantly better. Results: A total of 977 HNSCC patients constituted the study population. The cut-off values of sarcopenia were established at SMI 0.99). Considering these results, late dysphagia was analysed as well and results for grade≥2 and grade≥3 dysphagia were similar (6-24 months after RT). In addition, sarcopenic HNSCC patients experienced more physician-rated dysphagia during and after treatment than non-sarcopenic HNSCC patients (Figure 1). Conclusion: This study showed that sarcopenia in HNSCC patients undergoing RT was an independent prognostic factor for the development of physician-rated acute dysphagia grade≥3 and late dysphagia grade≥2 and grade≥3, which might be explained by its impact on the swallowing muscles. However, sarcopenia did not improve the performance of NTCP-models RT-induced other evaluated acute toxicities.