Material/methods: This was a retrospective analysis in a prospective cohort of HNC patients treated from January 2007 to December 2018 with (chemo)radiotherapy. Planning CT-scans were used for evaluating skeletal muscle mass. Characteristics of sarcopenic and non-sarcopenic patients were compared. The impact of sarcopenia was analysed by adding sarcopenia to the linear predictors of current NTCP models predicting physician- and patient-rated acute toxicities.
Results: The cut-off values of sarcopenia in the study population (n=977) were established at skeletal muscle index <42.0 cm2/m2 (men) and <31.2 cm2/m2 (women), corresponding to the lowest sex-specific quartile. Compared to non-sarcopenic patients, sarcopenic patients were more frequently smokers (61% vs. 48%, p<0.001), had more often advanced stage of disease (stage III-IV, p=0.004), higher age (67 vs. 63 years, p<0.001) and experienced more pretreatment complaints, such as dysphagia (grade ≥2, p<0.001). Sarcopenia remained statistically significant, next to the linear predictor, only for physician-rated grade ≥3 dysphagia (week 3-6 during RT, p<0.01). However, sarcopenia did not improve the performance of these NTCP models (p>0.99).
Conclusion: Sarcopenia in HNC patients was an independent prognostic factor for radiation-induced physician-rated acute grade ≥3 dysphagia, which might be explained by its impact on swallowing muscles. However, addition of sarcopenia did not improve the NTCP model performance.