ESTRO 2024 - Abstract Book

S2087

Clinical - Sarcoma, skin cancer, melanoma

ESTRO 2024

survival in our small cohort over a long follow up period. Using SFGRT and neoadjuvant CCRT appeared to be safe and should be tested on a larger population with locally advanced extremity STS.

Keywords: Sarcoma, GRID, SFGRT

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Clinical Outcomes in Osteosarcoma Patients Treated with Palliative Radiotherapy

Melisa Bagci Kilic 1 , Zerrin Ozgen 1 , Ece Ercan 2 , Zilan Baskan 1

1 Marmara University, Radiation Oncology, Istanbul, Turkey. 2 Marmara, University, Istanbul, Turkey

Purpose/Objective:

The combination of chemotherapy and surgery is the main treatment of osteosarcoma. Radiotherapy is generally used for palliation of metastatic disease or treating local recurrence. However, there are limited published data regarding experience with radiotherapy. We assessed the response to radiotherapy and the survival time of osteosarcoma patients after radiotherapy.

Material/Methods:

We retrospectively analyzed ten patients who were diagnosed with osteosarcoma and received radiotherapy at our institution between 2019 and 2023. Before radiotherapy, all patients underwent neoadjuvant chemotherapy and had wide tumor resection with endoprosthetic reconstruction for their primary tumors. A total of seventeen lesions were treated in these ten patients, with different dose fraction schedules based on the lesion location. Nine patients received radiotherapy for palliative symptom-alleviating intent for a total of 16 metastatic lesions. For these metastatic lesions, the median BED10 was 37.5 Gy (range: 17.25 - 50.70) and the median equivalent dose in 2 Gy fractions (EQD2) was 31.25 Gy (range: 14.38 - 42.25) with median number of fractions per course was 5 (range: 5 13). One patient received treatment for positive surgical margins with a total dose of 60 Gy delivered in 30 fractions, due to refusing the amputation.

Results:

Ten patients (9 males and 1 female) were included in the analysis, with a median age of 17 years (range 13-69). At the time of the diagnosis, three (30%) patients had metastatic disease. All patients who were treated for palliative intent had symptom improvement. Out of the fifteen lesions assessed radiologically, 11 (73.3%) showed a partial radiological response, while three (20%) remained stable. The patient who refused amputation had complete radiological response. For metastatic patients, the median survival after the start of the radiotherapy was 207 days, ranging from 76 to 567 days. No grade 2 or higher toxicities associated with radiotherapy were reported.