ESTRO 2020 Abstract book

S498 ESTRO 2020

PRO-CTCAE response pairs revealed steady decline of agreement between physician and patients from baseline towards the end of treatment across all domains, for ‘pain’ baseline and week 6 was 76.7% and 50% respectively. Patient reported toxicity grades were more than physicians in almost all domains. Decline of agreement was more prominent in the domains that are not easily evaluable by physical examination. Conclusion Comparison of Physician reported and patient reported chemoradiation induced acute toxicities reveals significant discrepancies of toxicity reporting with a possibility of under-assessment of the toxicities by physicians. Both the tools can complement each other for accurate assessment of toxicity grading and better management. PO-0839 Doses and Overlapping Volumes in Re- irradiation for Head and Neck Cancer A. Embring 1 , E. Onjukka 2 , S. Bornedal 2 , C. Mercke 3 , I. Lax 2 , B. Wennberg 2 , A. Berglund 4 , S. Friesland 3 1 Karolinska University Hospital, Department of Radiotherapy, Stockholm, Sweden ; 2 Karolinska University Hospital, Medical Radiation Physics and Nuclear Medicine, Stockholm, Sweden ; 3 Karolinska University Hospital, Department of Oncology, Stockholm, Sweden ; 4 Epistat, Epidemiology & Statistics Consulting, Stockholm, Sweden Purpose or Objective Local recurrence is the predominant pattern of failure after treatment of advanced head and neck cancer (HNC). With palliative chemotherapy only, these patients will have a median overall survival (OS) of 6-10 months. Several studies have shown that re-irradiation of recurrent HNC is a treatment option for selected patients. However, the definition of re-irradiation is often vague, or poorly defined in the literature and to our best knowledge, there are until now no published data on the impact of the overlapping re-treated volumes in re-irradiation of HNC. The aim of this study was to evaluate the treatment outcome after re-irradiation for HNC and determine some predictive factors, including cumulative dose-volume parameters. Material and Methods Fifty-five consecutive patients re-irradiated for HNC cancer between 2011-2017 in our institution were retrospectively analysed. Outcome data were collected from a local quality registry and supplemented with a review of medical records. Patients with an initial treatment of ≥60 Gy in EQD2 (α/β=3 Gy) and a re- treatment with an overlapping dose of ≥40 Gy in EQD2 were included in the study. In line with these inclusion criteria, V100 (EQD2) was considered the re-treated volume. Initial and re-treatment treatment plans were collected, and the 3D dose distributions converted to EQD2. A plan sum was then calculated following a non-rigid registration of the CT images, yielding the cumulative V100 for the analysis. Kaplan-Meier curves were plotted for cumulative OS and progression-free survival (PFS), considering the re- irradiation dose, re-treated volume, site of recurrence, performance status (PS) at re-irradiation and age as predictive variables. Results

The OS of all included patients at 2 and 5 years was 44% and 29% respectively and PFS at 2 and 5 years was 34% and 30% respectively. This study did not show any significant differences in OS or PFS in relation to PS, re-treated volume, site of recurrence, age or re-irradiation dose. The rate of fatal treatment-related adverse events was 5,5% (2 carotid blowouts and 1 acute radiation induced toxicity). Conclusion Re-irradiation should be considered for patients with recurrent or second primary head and neck cancer. There seems to be a benefit with respect to survival, which is in accordance with published data. This analysis did not demonstrate the impact of the re-treated volume. However, the calculation of the cumulative dose distribution is important and further analysis on its relation to side effects is ongoing. PO-0840 Sequential versus SIB IMRT for patients with nasopharyngeal carcinoma presenting cranial nerve palsy C. Huang 1 , S. Chou 1 , Y. Wang 1 , H. Hsu 1 , H. Chen 1 , F. Fang 1 1 Kaohsiung Chang Gung Memorial Hospital, Department of Radiation Oncology, Kaohsiung, Taiwan Purpose or Objective To evaluate the therapeutic outcome of sequential versus simultaneous integrated boost (SIB) intensity-modulated radiation therapy (IMRT) for patients with locally advanced nasopharyngeal carcinoma (NPC) presenting cranial nerve (CN) palsy. Material and Methods A total of 76 locally advanced NPC patients presenting CN palsy curatively treated by sequential-IMRT (n = 52) or SIB- IMRT (n = 24) from 2003 to 2015 were enrolled. Upper CN (II-VI) palsy was presented in 64 patients, lower CN (VII- XII) palsy in 4 patients, and both upper and lower CN palsy in 8 patients. Thirty-eight patients had CN palsy for more than 2 months before diagnosis. Median follow-up time for survived patients was 7.6 years. Overall survival (OS), locoregional progression-free survival (LRPFS) and distant metastasis-free survival (DMFS) were evaluated. The binary logistic regression, Kaplan-Meier method and Cox regression analyses were applied. Results The median OS was 5.0 years and recovery of palsy was observed in 35 patients. The actuarial 5-year OS, LRPFS and DMFS rates were 48.5%, 40.2% and 39.1%, respectively. Palsy duration less than 2 months was the most important prognosticator for recovery of palsy. In multivariate analysis, both SIB-IMRT and concurrent chemotherapy were the significant prognostic factors for better OS and LRPFS; N3 stage and sequential-IMRT were the prognosticators for worse DMFS. Conclusion Compared with sequential-IMRT, SIB-IMRT did not improve the recovery rate of cranial nerve palsy, but it was an important prognostic factor for better survival outcome.