S979
Clinical - Oligometastatic cancer
ESTRO 2026
primary disease.Prostate cancer was the most frequent primary histology in 48% of cases, followed by breast (26.9%), uterus (7.7%), NSCLC (5.7%). Median age was 70 years (range, 49-88), M=30;F=22.In the majority of patients (73%) SBRT was delivered to a single oligometastasis, with up to 4 NSBM treated simultaneously, being the thorax the most frequent site of SBRT (53.8%), followed by pelvis (46.1%). Concurrent systemic therapy was administered in 55.8% of patients.After a median follow-up of 31.8 months (range, 12-33.4), 1- and 2-years LC rates were respectively 98.1% and 96%, while DPFS rates were 57.7% and 31.5%. No significant predictors were found at statistical analysis1- and 2-years TNTS were respectively 82.7% and 42.9% with worse outcomes for patients with oligoprogressive disease (p=0.02).Concerning OS, 1- and 2-years rates were respectively 94.3% and 90%, with a statistically significant relation with male gender, likely reflecting prostate histology, for improved outcomes (p=0.00); also >1 metastasis treated reported a correlation with lower OS rates (p=0.02).Overall, prostate histology was associated with improved DPFS, OS, TNST (p=0.03, 0.03 and 0.001, respectively). No G ≥ 3 adverse events were observed, with 15.3% of cases developing acute G2 pain after SBRT, fully resolved after oral steroids. Conclusion: In our experience, SBRT for NSBM was safe and effective with minimal toxicity and excellent results in terms of LC. Prostate histology relates to improved outcomes and better disease control rates. Keywords: bone metastases; oligometastases; sbrt Safety and Effectiveness of All-in-one Emergency Radiotherapy in Metastatic Vertebral Malignancies Mao Li, Kangjia Pei, Hui Xiao, Weijuan Jiang, Jinna Li, Haitao Sun, Runhong Lei, Yongping Zheng, Ping Jiang, Chunxiao Li, Junjie Wang Department of Radiation Oncology, Peking University Third Hospital, Beijing, China Purpose/Objective: This study utilized an All-in-one (AIO) platform linac equipped with a fan-beam computed tomography (FBCT) system to investigate the practicality, safety, and effectiveness of intensity-modulated emergency radiotherapy in metastatic vertebral malignancy. Material/Methods: A cohort of patients with metastatic malignancies in the spinal column who were potential candidates for radiotherapy was established using a single-center dataset from April 17, 2024, to September 18, 2025. Informed consent was acquired before patients were included in this study and treated via AIO emergency Digital Poster 3344
achieves durable local control in oligometastatic disease, with 3-year local progression rates of 11.4%. Dose-response relationships confirm the critical importance of adequate minimum PTV doses. The observed differences between de novo and repeat oligometastatic disease, and across primary tumor types, suggest distinct biological behaviours that warrant consideration in treatment planning and trial design. These real-world data validate SBRT efficacy while identifying populations potentially benefiting from intensified local treatment strategies. Keywords: SBRT, metastases directed therapies, EORTC Stereotactic radiotherapy for non-spine bone metastases: a mono-institutional experience Francesco Cuccia 1 , Marina Campione 2 , Salvatore D'Alessandro 1 , Gianluca Mortellaro 1 , Antonio Spera 1 , Vanessa Figlia 1 , Daniela Cespuglio 1 , Francesco Azzarello 3 , Giuseppe Carruba 2 , Livio Blasi 4 , Giuseppe Ferrera 1 1 Radiation Oncology, ARNAS Civico Hospital, Palermo, Italy. 2 Clinical Research, ARNAS Civico Hospital, Palermo, Italy. 3 Medical Physics, ARNAS Civico Hospital, Palermo, Italy. 4 Medical Oncology, ARNAS Civico Hospital, Palermo, Italy Purpose/Objective: Stereotactic body radiotherapy (SBRT) has entered daily clinical practice in the management of Digital Poster 3181 oligometastatic disease. Similarly to the evidence in support of spinal metastases, the use of SBRT has been recently reported also for the treatment of non- spinal bone metastases (NSBM) Material/Methods: This is a mono-institutional experience of oligometastatic patients treated with SBRT for NSBM. Primary endpoint of the study was local control (LC); acute and late toxicity, distant progression-free survival (DPFS), time-to-next systemic treatment (TNST), polymetastatic-free survival (PMFS) and overall survival (OS) were secondary endpoints. Toxicity was assessed according to CTCAE criteria v5.0. Survival estimates were performed using Kaplan Meier A total of 74 bone oligometastases in 52 patients were treated in our institution between February 2020 and December 2024. All patients received SBRT with Helical Tomotherapy for a median total dose of 32 Gy (range, 24-35 Gy) delivered in 3-5 fractions. In 51.9% of cases, SBRT was delivered to oligoprogressive lesions, oligorecurrent in 42.3% while the remaining were patients with synchronous oligometastases and method. Results:
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