ESTRO 2023 - Abstract Book

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ESTRO 2023

The mean dose to both OARs was significantly higher in the ASP group compared to the CONTR group (10.2 Gy vs 7.3 Gy, p=0.013 for brainstem, 60.8 Gy vs 52.2 Gy, p=0.001 for swallowing muscles). Dose levels in the PSWAL group were very similar to the CONTR group (7.7 Gy vs 7.3 Gy, p=0.3, 52.2 Gy vs 52.2 Gy,p=0.5). Correlation between dose in the swallowing muscles and brainstem was high, with a Pearson correlation coefficient of 0.51, p<0.001 (Figure). From the data plot we observed that 8 out of the 9 case/control ASP patients with a mean dose >13 Gy to the inferior brainstem were cases with aspiration

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Conclusion Aspiration significantly correlated with both dose in the swallowing muscles and dose to the inferior brainstem, whereas painful swallowing did not correlate with any of the evaluated OARs and showed similar dose levels in controls and cases. Swallowing muscles are broadly recognized as OAR for treatment planning, however, the brainstem is not. Further research to develop clinical dose constraints for the inferior brainstem to aim at reduction of late aspiration risks is indicated.

PO-1177 The role of SABR in the management of oligometastatic and recurrent head and neck cancers

A.A. Mohamed 1 , M. Schlenter 1 , C. Sorge 1 , M. Tometten 2 , S. Hackenberg 3 , M. Goncalves 3 , F. Hölzle 4 , M. Eble 1

1 RWTH Aachen University Hospital, Department of Radiation Oncology, Aachen, Germany; 2 RWTH Aachen University Hospital, Department of Hematology, Oncology and Stem Cell Transplantation, Aachen, Germany; 3 RWTH Aachen University Hospital, Department of Oto-Rhino-Laryngology - Head and Neck Surgery, Aachen, Germany; 4 RWTH Aachen University Hospital, 4Department of Oral and Maxillofacial Surgery, Aachen, Germany Purpose or Objective Stereotactic ablative body radiotherapy (SABR) has emerged as a local ablative tool in the management of oligometastatic disease (OMD). However, prospective studies in this indication were almost tumor-agnostic. Further, evidence of the impact of SABR in the management of oligometastatic /recurrent head and neck cancer is scarce. In the current analysis, we are reporting a single-center experience about the efficacy of SABR in this subset of patients Materials and Methods We retrospectively analyzed all the head and neck cancer patients from 1/2015 till 09/2022 in our registry, who received SABR through the course of their treatment. Patients were considered eligible for the analysis when SABR was applied for 1-5 metastatic sites (oligometastatic) or to regional recurrence after primary treatment. Synchronous OMD was considered when the metastasis was diagnosed till 3 months after the initial diagnosis and metachronous OMD was diagnosed after 3 months. Endpoints for the analysis were the local control (LC), progression-free survival (PFS) overall survival (OS), and systemic therapy-free survival. Results Twenty-four patients with 37 lesions (31pulmonary lesions, 4 mediastinal lymph nodes and 1 suprarenal metastasis, and one regional recurrence in the base of the tongue) met the criteria for the analysis. seventeen patients were diagnosed with metachronous OMD, 6 patients with synchronous OMD, and one patient with oligo-recurrence. Nineteen Patients with 31 lesions had squamous cell carcinoma histology and 5 patients with 6 lesions had other histology. The median prescribed dose as EQD2 α ⁄ β 10 was 88 Gy (range 48-93.8), in median 3 fractions (range 1-8). LC at 6 months, 1, and 2 years was 93.2%, 89%, and 83% respectively. The median PFS and OS were 14 & 35.3 months respectively. The median systemic therapy-free survival was 28.13 months (figure)

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