S983
Clinical - Oligometastatic cancer
ESTRO 2026
2 Radiation Oncology, Acibadem Maslak Hospital, Istanbul, Turkey
label trial. Lancet. 2019 May 18;393(10185):2051-2058. doi: 10.1016/S0140-6736(18)32487-5. Epub 2019 Apr 11. PMID: 30982687.2. Ugurluer G, Mustafayev TZ, Gungor G, et al. Stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of liver metastases in oligometastatic patients: initial clinical experience. Radiat Oncol J. 2021 Mar;39(1):33- 40. doi: 10.3857/roj.2020.00976. Epub 2021 Mar 26. PMID: 33794572; PMCID: PMC8024184. Keywords: liver metastases, SMART, oligometastatic cancer 1.5T MR-guided adaptive stereotactic radiotherapy for liver metastases with intrafraction tracking and gating using Comprehensive Motion Management Chiara De-Colle 1 , Michele Rigo 1 , Andrea Gaetano Allegra 1 , Niccolò Giaj-Levra 1 , Luca Nicosia 1 , Carolina Orsatti 1 , Edoardo Pastorello 1 , Francesco Ricchetti 1 , Andrea Romei 1 , Nicola Bianchi 1 , Riccardo Filippo Borgese 1 , Antonio De Simone 1 , Davide Gurrera 1 , Stefania Naccarato 1 , Gianluisa Sicignano 1 , Roberto Pellegrini 2 , Ruggero Ruggieri 1 , Filippo Alongi 1,3 Digital Poster 3712 1 Advanced Radiation Oncology Department, IRCCS Sacro Cuore Don Calabria Hospital, Negrar, Italy. 2 Medical Affairs, Elekta AB, Stockholm, Sweden. 3 University of Brescia, University of Brescia, Brescia, Italy Purpose/Objective: Stereotactic body radiotherapy (SBRT) is a well- established treatment option for liver oligometastases, with a correlation between biologic effective dose and outcome. Nevertheless, accurate respiratory motion management is required. MR-Linac allows for improved target delineation accuracy due to high soft tissue image quality compared to CT. Comprehensive motion management (CMM) may improve safety and efficacy, enabling GTV-PTV margin reduction and dose escalation. Nonetheless, some challenges i.e. the treatment time, need investigation. Here we report our experience of liver SBRT at the MR-Linac using the CMM. Material/Methods: In September 2023 CMM was installed and used for liver SBRT at our MR-Linac. Patients had the following characteristics: >18 years; Child-Pugh ≤ B7; enough reserve of non-irradiated liver (>700cc). Exclusion criteria were contraindications to MRI. Patients were simulated supine, arms down, in free-breathing with abdominal compression belt. Isotropic 5mm PTV expansion was added to the GTV. Adapt-to-shape or adapt-to-position workflows were chosen based on daily anatomy. We report on patients and treatment
Purpose/Objective: Stereotactic body radiotherapy (SBRT) is increasingly utilized in the setting of oligometastatic disease with improved survival [1], including liver metastases. Stereotactic MR-guided Adaptive Radiotherapy (SMART) is a promising technique with enhanced soft tissue visualization, online adaptive plannıng and motion management [2]. This single-institution study aims to evaluate the clinical outcomes, safety and efficacy of SMART for liver metastases. Material/Methods: In this IRB approved study, we retrospectively analyzed 102 patients (199 lesions) who underwent SMART for liver metastases between September 2018 and September 2025. A total of 199 lesions were treated in 128 SBRT courses. Overall survival (OS) and distant progression-free survival (DPFS) were calculated on a per-patient basis and local control (LC) was calculated on a per-lesion basis while intrahepatic progression-free survival (IHPFS) was calculated on a course basis using the Kaplan-Meier method. Toxicities were graded per CTCAE v5.0. Results: Median follow-up was 22 months (range, 2-83 months). Median lesion diameter was 17 mm (range, 4-100 mm). Median prescribed dose was 45 Gy (range, 20-60 Gy) in 5 (range, 1-10) fractions. Median BED10 was 100 Gy (range, 48-151.20 Gy). A total of 802 fractions were conducted of which 752 (93.77%) were online adapted. In 48 (37.5%) of courses, liver had already received a local treatment (operation, RFA, SBRT etc..) and 16 (8%) of the lesions received prior local treatment of which four were SBRT. Lesion-based one- and two-year LC rates were 96.3% and 95.3%, respectively. Local progression occurred in 9 lesions despite BED10 was ≥ 100 Gy in all cases. Median IHPFS was 11 months with one- and two-year IHPFS rates of 39.8% and 44.7%. Median DPFS was 9 months with one- and two-year DPFS rates of 43.7% and 20.1%. Median OS was 43 months, with 1- and 2-year OS rates of 75.4% and 66.9%. No grade ≥ 3 toxicity was observed, and grade 1–2 acute toxicities subsided within one month. Conclusion: SMART outstands as a promising non-invasive technique for ablative treatment of liver metastases. Future studies could are warranted to enlighten its relation with novel systemic treatments and the effect of dose/fractionation regimens. References: 1. Palma DA, Olson R, Harrow S, et al. Stereotactic ablative radiotherapy versus standard of care palliative treatment in patients with oligometastatic cancers (SABR-COMET): a randomised, phase 2, open-
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