This study aimed to classify patients who underwent stereotactic body radiotherapy (SBRT) for oligometastatic disease (OMD) at our institution using the consensus classification proposed by the European Society for Radiotherapy and Oncology and the European Organization for Research and Treatment of Cancer (ESTRO–EORTC) and to evaluate clinical outcomes based on this classification. Patients diagnosed with extracranial OMD who underwent SBRT, regardless of the primary tumour site, between April 2020 and December 2022 were retrospectively analysed. Based on the ESTRO–EORTC classification, cases were categorised into three OMD states: de novo, repeat, and induced OMD. We assessed overall survival (OS), local recurrence (LR) rates, and treatment-related adverse events (AEs). A total of 60 patients with 70 lesions were included, with a median follow-up of 24 months. All lesions were successfully classified according to the ESTRO–EORTC classification: 37 as de novo, 20 as repeat, and 13 as induced OMD. SBRT was delivered using the CyberKnife® system, with a median dose of 35 Gy in five fractions. The median OS for all patients was 71 months. The 1- and 2-year LR rates were 7.6% and 12%, respectively. Among OMD states, induced OMD had the poorest OS (median: 41 months), compared with de novo OMD (not reached) and repeat OMD (71 months). Only one Grade ≥ 3 AE was observed. All SBRT-treated OMD cases at our institution were successfully classified using the ESTRO–EORTC system. The classification showed potential prognostic value, suggesting its utility for stratifying patients with OMD.
Goto et al. (2026) studied this question.