ESTRO 2021 Abstract Book

S605

ESTRO 2021

patients had VHI score >30 (moderate or serious voice handicap) at 3 years, compared to 38% at baseline. VHI >30 was more frequently reported in patients with any late grade 3 toxicity, compared to those without (60% vs. 22% at 18 months, p<0.05). (See figure).

Conclusion Local control rate and laryngectomy-free survival of SVCI are excellent with favorable toxicity profile and good VHI-score. These results validate our early results and compare favorably to those of patients treated to the whole larynx with a conventional scheme of 66 Gy in 33 fractions at our institute. PD-0774 Impact of sarcopenia on acute radiotherapy-induced toxicity in head and neck cancer patients E. Karavolia 1 , M.I. van Rijn-Dekker 1 , L. Van den Bosch 1 , J.G. van den Hoek 1 , E. Oldehinkel 1 , T.W. Meijer 1 , J.A. Langendijk 2 , R.J. Steenbakkers 1 1 University Medical Center Groningen (UMCG), Radiation Oncology, Groningen, The Netherlands; 2 University Medical Center Groningen (UMCG), Radiation oncology, Groningen, The Netherlands 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<42.0 cm 2 /m 2 (men) and SMI<31.2 cm 2 /m 2 (women), according to the lowest gender specific quartile. Compared to non-sarcopenic patients, sarcopenic patients were more likely to smoke (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 baseline complaints, like dysphagia (grade≥2, p<0.001) (Table 1) . Among all analysed toxicities, sarcopenia only remained statistically significant for RT-induced physician-rated dysphagia grade≥3 (week 3-6 during RT, p<0.01). However, the performance of the NTCP models did not improve (p>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 ).