The role of SBRT as an ablative treatment in oligometastatic patients

Extracranial oligometastatic disease, defined as up to five metastases, represents an intermediate cancer state with potential for long-term control. Stereotactic body radiotherapy (SBRT) is a non-invasive treatment associated with high local control, limited toxicity, and the ability to delay systemic therapy. This study reports institutional outcomes of SBRT across oligometastatic scenarios.

We retrospectively analyzed 259 patients with 401 extracranial oligometastatic lesions from solid tumors treated with SBRT between 2016 and 2022. Patients were classified according to the ESTRO-EORTC consensus as oligorecurrence, oligoprogression, or oligopersistence, and as synchronous or metachronous. The eligibility criteria included ECOG 0-1, life expectancy > 6 months, ≤ 5 treatment-naïve extracranial metastases, and no intracranial disease. Survival outcomes were estimated using the Kaplan-Meier method.

After a median follow-up of 68.7 months, SBRT achieved durable local control exceeding 80% beyond 4 years across all metastatic sites, with lung and lymph node lesions showing the best outcomes. Overall disease control declined due to new metastases; however, over 40% of lesions remained progression-free at 6 years. Superior outcomes were observed in patients with genuine oligometastatic disease, de novo or synchronous presentation, and fewer treated lesions. Median overall survival (OS) was 93.8 months (95%CI 81.1-106.4) and was longer in patients with initially locoregional disease and prostate cancer.

In this retrospective single-center experience, SBRT achieved durable local control with acceptable toxicity in selected patients with extracranial oligometastatic disease. These findings are consistent with previously published series and support the role of SBRT as a metastasis-directed approach in carefully selected patients. Prospective studies are needed to better define prognostic subgroups and optimize patient selection.