ESTRO 2020 Abstract Book

S453 ESTRO 2020

Results

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.

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 PO-0841 Treatment failure patterns after radical radiotherapy using modern radiation techniques. C.A.D.N. Laranja 1 , I. Rodrigues 1 , T. Ramos 1 , B. Castro 1 , F. Sousa 1 , D. Moreira 1 , I. Reis 1 , A. Soares 1 1 Instituto Português de Oncologia do Porto, Radioterapia externa, Porto, Portugal Purpose or Objective The recommended treatment in head and neck cancer (HNC), mainly in advanced stages involves an association of radiotherapy (RT) and Chemotherapy. However, locoregional recurrences are seen in 15 to 50 percent of these pts. Recurrent disease is an important cause of morbidity and mortality with impact in long term survival. The aim of this study was to assess patterns of locoregional treatment failure in HNC patients (pts) treated with radical RT using modern radiation techniques (3DCRT, IMRT and VMAT). Focus was given on the relation between treatment volumes, dosimetry and local of recurrence/persistence. We also analyzed the impact of treatment failure, in terms of overall survival(OS) and locoregional control (LRC) Material and Methods Retrospective analysis of 314 pts treated between January 2015 and December 2018. Only pts with squamous cell tumors of Larynx, Oropharynx and Hypopharynx were included. Our analysis considered recurrent disease, pts who had at least one imagiologic control exam after the end of RT with no evidence of disease before the relapse, otherwise was considered persistent disease. Completing the prescribe treatment dose (63Gy for Larinx and 50-70Gy for Oropharynx and Hypopharinx) was an inclusion criteria of our study. Planning target volume (PTV) 70 was defined Abstract withdrawn