ESTRO 2020 Abstract book

S21 ESTRO 2020

Structures (DARS) were delineated on the planning CT images. Normal Tissue Complication Probability (NTCP) was calculated using biological modeling with Equivalent Uniform Dose (EUD). Results A total of 52 patients were included in the study. Oral cavity was the most common site with 45 patients (85%) and 77% of the patients had primary surgery prior to Re RT. The median Re RT dose, number of fractions and duration was 60Gy (IQR 60-64Gy), 30 (IQR 30-32) and 44 days (IQR 42-48 days) respectively. Median PTV volume was 480 (304-608.7)cc. Feeding tube was present in 54.9% and 25.2% at baseline, and first follow-up respectively. The QOL domain scores and swallowing scores are given in the table 1. The NTCP and EUD for TD 47 and TD 50 were 25.1%, 3.7% and 42Gy, 40.8Gy respectively. Logistic regression analysis showed a significant correlation of DARS V30, V40 and V50 with the presence of feeding tube at first follow-up. There was also a significant correlation between the DARS V30, V40, V50, mean dose and PTV volume with the first follow-up HNSW QOL score.

Manchester, United Kingdom ; 2 The Christie NHS Foundation Trust, Christie Radiotherapy, Manchester, United Kingdom Purpose or Objective Patients (pts) with Head and Neck SCC (HNSCC) may present with marked symptoms of pain and swallowing dysfunction. Few patient-reported outcome measures (PROMS) are available to quantify the effects of (chemo)radiotherapy ((CT)RT) on baseline symptoms, despite this being an important part of discussion during consent for therapy. The aim of this study was to determine the acute and late effects of (CT)RT on baseline symptoms in pts with HNSCC in clinical practice. Material and Methods All pts who completed a MD Anderson Symptom Inventory Head and Neck (MDASI-HN) questionnaire prior to (CT)RT for HNSCC, plus at least one post treatment time point (6- 9 weeks (wks), 10-19 wks, 20-39 wks and 40-78 wks after RT) from 2016-19 were considered. Any with subsequent disease relapse were excluded. Pts were considered symptomatic at baseline if a score was >/= 5 (moderate symptom burden) and dichotomised accordingly for that subscale. Clinically relevant MDASI-HN questions were considered: symptom subscales of pain, dry mouth, difficulty swallowing/chewing and difficulty with voice/speech and interference subscales of mood and enjoyment of life. The difference in PROM score evolution between patients with high and low initial symptom burden was assessed via likelihood ratio test of a linear mixed model containing baseline score as a fixed effect to one without. Patient identity was included as a random effect to account for individual differences. Results 320 patients were analysed (Table 1). A significant difference in overall score evolution after RT for all subscales (p<0.001) was shown (Figure 1). Those pts with moderate or severe symptoms at baseline in pain, difficulty swallowing/chewing, difficulty with voice/speech subscales experienced a reduction in scores by 6 wks post RT. Decreases persisted throughout follow- up (FU), with the latter continuing to improve. Similar trends are seen in both interference subscales. Dry mouth scores in pts with moderate or severe symptoms at baseline do not significantly change after RT. In contrast those with low symptoms at baseline described a worsening of symptoms acutely post RT. In pain and difficulty with voice/speech subscales these return to baseline, while scores in dry mouth and difficulty with swallowing/chewing remain elevated throughout FU. For all subscales pts who were symptomatic pre-treatment continued to rate their symptoms more highly throughout FU. Although a smaller variation at 40-78 wks is seen, there is still a significant difference between groups in all subscales (p<0.05) except pain (p=0.058).

Conclusion There is a significant impact of the DARS dosimetric parameters on the swallowing outcomes in Re RT for head neck cancers. These parameters are however, different from those known to influence outcomes in the per primum setting. V30, V40 and V50 should be minimized to ensure good swallowing outcomes in these patients. PD-0054 Baseline symptom burden predicts patient reported well-being following curative (chemo)radiotherapy C. Barker 1 , G. Price 2 , K. Garcez 1 , L. Lee 1 , A. Sykes 1 , D. Thomson 1 , A. McPartlin 1 1 The Christie NHS Foundation Trust, Clinical Oncology,

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