S995
Clinical - Oligometastatic cancer
ESTRO 2026
Radiation Oncology, Biology, Physics (2025). Keywords: SABR, Bone metastases
Digital Poster Highlight 4997 Predictors of Local Control after SBRT for Oligometastatic Cancer: A Large-Scale Analysis of 1909 patients Beatrice Marini 1 , Davide Franceschini 1 , Antonio Marco Marzo 1 , Ruggero Spoto 1 , Luca Dominici 1 , Marie Lohmer 1 , Stefano Tomatis 1 , Ciro Franzese 1,2 , Marta Scorsetti 1,2 1 Radiotherapy and Radiosurgery Department, IRCCS Humanitas Research Hospital, Rozzano (MI), Italy. 2 Department of Biomedical Sciences, Humanitas University, Pieve Emanuele (MI), Italy Purpose/Objective: Stereotactic Body Radiation Therapy (SBRT) has emerged as a standard local ablative treatment for patients with oligometastatic disease. This study aims to assess local control (LC) outcomes across a large cohort and to identify predictive factors for LC. Material/Methods: Eligibility criteria included ≤ 5 metastatic lesions, controlled primary tumour, and adequate performance status. Lesions included were in different sites from different primary tumours. SBRT was delivered with a prescribed dose according to lesion size, location, and proximity to organs of interest. Primary endpoint was local control (defined as absence of in-field progression on follow-up imaging). Potential predictive factors for LC were analysed using univariate (Kaplan–Meier, log-rank tests) and univariate/multivariate (Cox proportional hazards regression) analyses when appropriate Results: Between January 2013 and February 2025, 1909 patients with 2991 oligometastatic lesions were treated with SBRT. Patients and treatment characteristics are reported in Table 1. After a median follow-up of 24.5 months, the 1-, 3-, and 5-year LC rates were 91%, 81% and 76%.
Univariate analysis using logrank test showed that previous local ablative treatments (p=0.023), previous line of systemic therapy (p=0.048), number of lesions (p<0.001), type of oligometastatic disease (p=0.0126), concomitant systemic therapy (ST) (p=0.021) and primary tumour site (p<0.001) significantly influenced LC, while higher BED (HR=0.996; p=0.018) and longer disease free interval (HR=0.96; p=0.032) were associated to a reduced risk of local failure. As expected, patients achieving a complete response (CR) showed a significantly improved LC compared with those with partial or stable responses (p<0.001).In the multivariate Cox model, BED (HR=0.99; 95%CI 0.986– 0.994; p<0.001), concomitant ST (HR=0.65; 95% CI 0.48–0.87; p=0.004), more than three irradiated lesions (HR 1.78; 95% CI 1.26–2.54; p=0.01), repeat recurrences (HR=1.60; 95%CI 1.09 – 2.34; p=0.016), were significantly associated with local control. Primary tumor sites other than colorectal cancer were associated with a higher local control (HR ranging between 0.45–0.60; p<0.05). The figure below report Kaplan–Meier curve of local control between patients stratified by primary tumor site (Colorectal primary / Other primaries)
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