ESTRO 2023 - Abstract Book

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ESTRO 2023

The median follow-up was 33 months (range 14 – 62). Regarding clinical outcomes, 4 patients showed improvement in pre radiosurgery symptoms, 2 patients remained symptom-free, and 2 patients demonstrated neurological stability. All tumors revealed regression (n=5) or stable dimension (n=3) during follow-up MRI, with a local control rate of 100%. Treatment related acute side effects included nausea grade ≤ 2 (3 patients), vomiting grade 2 (1 patient) and headache grade ≤ 2 (3 patients), that were easily manageable with conservative treatment. There were no grade 3 or 4 toxicities. There were no late side effects reported. Conclusion Robotic Stereotactic Radiosurgery seems to be a helpful therapeutic approach in the management of temporal bone paragangliomas, either after surgery and/or embolization recurrences or as a single and radical treatment, and may be a useful alternative to surgery in such cases. The location and shape of these tumors are a challenge in radiotherapy planning, and robotic stereotactic radiosurgery showed to be safe and effective in our series of patients. Additional follow-up and a larger patient population are required to confirm these favorable outcomes. 1 Vall d'hebron Hospital, Radiation Oncology, Barcelona, Spain; 2 Vall d'hebron Hospital, Radiation Oncology, Barcelona , Spain; 3 Vall d'hebron Hospital, Physics, Barcelona , Spain; 4 Vall d'hebron Hospital , Physics, Barcelona, Spain; 5 Vall d'hebron Hospital, Oral and Maxillofacial surgery, Barcelona, Spain; 6 Vall d'hebron Hospital, Medical Oncology, Barcelona, Spain Purpose or Objective Radiotherapy (RT) plays a fundamental role in the definitve treatment of squamous cell carcinoma of the head and neck. Despite optimal initial treatment, approximately 30-40% of patients will experience a locoregional relapse or second primary tumour. The management of this presents a major clinical challenge when re-treating an already irradiated field where the balance between the benefit to the patient vs. the risk of toxicity is narrow. With this analysis we aim to provide data to facilitate a rigorous selection and stratification of patients who could benefit from re-irradiation treatment. Materials and Methods We retrospectively analysed a series of patients with loco-regional relapse or 2nd primary head and neck cancer who were reirradiated between 2009-2021 in a previously irradiated field ( ≥ 50Gy) using 3D or IMRT and conventional fractionation. Data on disease-free survival (DFS), overall survival (OS), acute and chronic toxicity are presented. Results 55 patients were analysed. 20 patients (36%) were reirradiated within two years after the first irradiation, 35 (64%) after 2 years and none before 6 months. Almost the entire sample had an ECOG performance status ≤ 1 (n=54) at the time of reirradiation, demonstrating in the multivariate analysis performed that it is related to an improvement of the OS (HR 0.66, CI 0.29-1.52, p=0.33).Figure 1 shows the OS as a function of this time between initial treatment and reirradiation, showing a positive trend when the retreatment time is longer than 2 years, although it does not show statistical significance. The most frequent location was the oral cavity (n=21, 39%). Most of them underwent adjuvant RT (n=32, 58%), reaching a mean dose of 59.95Gy (70.00-48.40) in addition to concomitant chemotherapy (67%). As we can see in figure 2 OS increase at doses above 50Gy. Regarding toxicity, the most frequent was acute toxicity (95%) in terms of mucositis and dermatitis G1 G2 according to the CTCAE v4.0 scale, 49% and 60% respectively. The incidence of chronic toxicity was 74%, with 9% G3-G4 trismus, 6% G3-G4 osteoradionecrosis and 36% G3-G4 dysphagia of which, 28% of the patients required gastrostomy placement due to RT. The Median DFS after completion of reirradiation was 4.7 months (range 1-110) and median OS after reirradiation was 17.1 months (1-130). PO-1203 Reirradiation in head and neck cancer. Who would benefit? Retrospective analysis of our experience R. Granado 1 , F. Pires 2 , S. Benavente 2 , M. Hermida 3 , D. Sanchez 4 , A. de Pablo 5 , J.D. Assaf 6 , I. Braña 6 , J. Giralt 1