ESTRO 2023 - Abstract Book

S1045

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ESTRO 2023

78% of treated patients did not develop new lesions during follow-up. Thirty new brain lesions appeared in 23 patients, 83% of them in the first year after FSRT. Median time to appearance was 5 months (range 1-28). Brain progression-free survival (BPFS) at 1 and 2 years were 98% and 86% in FSRT alone and 70% and 48% in adjuvant FSRT, respectively. Larger volumes of PTV were associated with the appearance of new brain metastases (p=0.026). Only three lesions (2.9%) presented necrohemorragic events, one requiring surgery. Two patients had seizures (2.7%) and a cerebral edema was also observed (0.97%). No patients presented ≥ grade 3 late toxicity.

Conclusion FSRT for brain metastases achieved a satisfactory local control and DSS with minimal risk of severe toxicity in OM and OP scenarios. Association with ICI achieves promising results in terms of local control. More than two-thirds of patients did not present new brain lesions after FSRT.

PO-1304 Thymoma: a single centre 10 year retrospective review

A. Cooper 1 , T. Evans 1 , I. Phillips 1 , S. Harrow 1 , J. Leach 1

1 Edinburgh Cancer Centre, Oncology, Edinburgh, United Kingdom

Purpose or Objective Thymomas are rare neoplasms originating from the thymus gland in the anterior mediastinum. They represent a heterogeneous group of intrathoracic malignancies with variable clinical management dependent on tumour resectability. The aim of this retrospective study was to review management strategies for patients diagnosed with thymoma, comparing regional clinical practice to European guidelines. Materials and Methods Patients with pathologically confirmed thymoma between 2009-2019 referred from across 5 health-boards in Scotland were identified from pathology coding. 85 patients were identified and their clinical records were reviewed. One patient was excluded as investigations concluded an alternative diagnosis, and 1 patient had 2 synchronous thymomas of different grading. The Masaoka-Koga staging system was used for thymoma staging. Results 83 patients were included with a mean age of 58.7 years at diagnosis. 48 patients (58%) had a diagnosis of myasthenia gravis (MG) or other associated autoimmune condition. 37 (45%) presented with local symptoms and 15 (18%) were detected incidentally. The most common WHO subtype was AB (26%), followed by B2/B3 (14%); 2 were thymic carcinoma. At diagnosis, 46% had stage IIA disease and 12% had stage IV disease. 96% of patients with early stage disease (stage I-III) underwent surgery. Neoadjuvant chemotherapy (NACT) was considered in patients with inoperable or advanced disease. Adjuvant treatment was recommended based on pathological outcome (table 1). 3% of patients with stage I-III disease died of a thymoma related death compared with 60% of patients with stage IV disease. Table 1. Thymoma management STAGE NACT Surgical resection Adjuvant radiotherapy Definitive radiotherapy Adjuvant SACT Recurrence Thymoma related death I n=22 1 21 1 0 0 0 1 IIa n=38 0 37 3 1 0 0 1 IIB n=8 0 8 2 0 0 0 0 III n=2 0 2 1 0 0 0 0 IVA n=5 2 4 1 1 1 1 3 IVB n=5 1 5 2 0 1 1 3 Not staged n=3 0 0 0 0 0 0 0