ESTRO 2025 - Abstract Book

S1391

Clinical - Lung

ESTRO 2025

References: 1. Siva S, et al. Single-Fraction vs Multifraction Stereotactic Ablative Body Radiotherapy for Pulmonary Oligometastases (SAFRON II). JAMA Oncol. 2021;7(10):1476-1485. 2. Videtic GM, et al. Long-term Follow-up on NRG Oncology RTOG 0915 (NCCTG N0927). Int J Radiat Oncol Biol Phys. 2019;103(5):1077-1084. 3. Singh AK, et al. One Versus Three Fractions of Stereotactic Body Radiation Therapy for Peripheral Stage I to II Non-Small Cell Lung Cancer: A Randomized, Multi-Institution, Phase 2 Trial. Int J Radiat Oncol Biol Phys. 2019;105(4):752-759. 4. Videtic GMM, et al. Ten-Year Experience in Implementing Single-Fraction Lung SBRT for Medically Inoperable Early-Stage Lung Cancer. Int J Radiat Oncol Biol Phys. 2021 Oct 1;111(2):436-442.

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Digital Poster Clinical outcomes of stereotactic body radiotherapy for oligometastatic non-small cell lung cancer: a Japanese institutional study Nao Mamuro 1 , Noriko Kishi 1 , Masahiro Yoneyama 1 , Yukinori Matsuo 2 , Takashi Mizowaki 1 1 Radiation Oncology, Kyoto University Hospital, Kyoto, Japan. 2 Radiation Oncology, Kindai University Faculty of Medicine, Osaka, Japan Purpose/Objective: We retrospectively investigated the efficacy and safety of stereotactic body radiotherapy (SBRT) for oligometastatic non-small cell lung cancer (OM-NSCLC). Material/Methods: The eligible patients were those who were treated with SBRT for OM-NSCLC, defined as having 1–3 metastases, between April 2022 and July 2024 at our institute. Patients with a prior history of radiotherapy to any lesions, except for brain metastasis, were excluded. For patients who received multiple courses of radiotherapy during the period, only the initial treatment was analyzed. The following variables were collected from medical records: age, sex, histology, classification of oligometastasis, sites of irradiated lesions, treatment details, overall survival (OS), progression-free survival (PFS), and toxicities. The cut-off date was set as September 30, 2024. Results: Twenty-five patients with 30 lesions were eligible for analysis: 15 males and 10 females with a median age of 69 years (range, 47–79 years). The breakdown of histology was as follows: adenocarcinoma in 17 patients, squamous cell carcinoma in 7 patients, and non-specified in 1 patient. The classifications of oligometastasis were: synchronous in 1 patient, repeat oligorecurrence in 2 patients, induced oligoprogression in 10 patients, induced oligopersistence in 6 patients, metachronous oligorecurrence in 3 patients, and metachronous oligoprogression in 3 patients. The sites of the irradiated lesions were as follows: lung (9 patients), bone (8 patients), chest wall (5 patients), lymph nodes (5 patients), adrenal glands (2 patients), and liver (1 patient). Prior systemic treatments were administered in 17 patients (68%): immune-checkpoint inhibitors (ICIs) in 8 patients, and tyrosine kinase inhibitors (TKIs) in 9 patients. The median follow-up period was 12.9 months (95% confidence interval, 7.4–18.4 months). The OS rates at 6 months and 12 months were 100 % and 92.3%, respectively. The PFS rates at 6 months and 12 months were 76.9% and 51.2%. No grade 2 or higher toxicities were observed, irrespective of prior use of ICIs or TKIs. Conclusion: OS and PFS after SBRT for OM-NSCLC were comparable with previous phase II studies, with no serious adverse events observed.