S1100
Clinical – Upper GI
ESTRO 2026
Digital Poster 3364
patients.Standard of care consist of systemic treatment, while the benefit of local consolidation is debated. The aimof this study is to investigate the use of SBRT for ILR from PC. Material/Methods: Methods: Clinical and treatment-related data from a consecutive cohort of PC patients receiving SBRT forILR following curative-intent treatment to the primary tumor were retrospectively collected. FollowingSBRT, local (in-field) relapse was defined as disease progression within the 50% isodose of the SBRTtreatment, while distant relapse was defined as both visceral (including peritoneal carcinosis) and/or nodal(out of field) progression. Statistical analysis was performed to assess the correlation between clinicalvariables and Local Control (LC), Progression- Free Survival (PFS) and Overall Survival (OS) Results: Results: Between July 2021 and February 2025, 14 patients received SBRT for ILR following surgery (n=12)or radiotherapy (n=2). Median follow-up was 9 (range 1-32) months. Median interval from curativetreatment to ILR was 23 (range 6-61) months. Increased CEA and/or Ca19.9 levels were observed in 7patients. Based on target location and proximity of organs of interest, active motion management wasapplied in 11 patients, consisting of robotic real- time tumor tracking (rRTTT) using surgical clips assurrogate fiducial markers (n=5), deep inspiration breath-hold (n=5) or abdominal compression (n=1); anITV-based approach in free breathing conditions was applied in the remaining patients (n=3). A totaldose of 35 Gy in 5 fraction (BED=59.5 Gy 10 ) was delivered in all cases. One-year LC, PFS and OSrates were respectively 69%, 31% and 49%. Abnormal CEA levels but not Ca19.9 were correlated withpoorer PFS (p=0.0061). Pattern of first failure after SBRT was distant, local and local+distant in respectively 7, 3 and 1 patients.Acute side effects included Grade 2 nausea, diarrhoea and abdominal pain in respectively 1,1 and 2patients. One late Grade3 adverse event (duodenal stenosis requiring stent positioning), was observed in a previously-irradiated patient. Conclusion: Conclusions: SBRT delivering a dose intensive schedule for ILR from PC after initial curative-intenttreatment provides acceptable LC rates. Due to high rate of distant failure, criteria for patient selectiondeserve further investigation. Caution is advised in case of prior radiotherapy. In selected cases, rRTTTusing surgical clips as surrogate fiducial markers obviate the need for further invasive procedures. Keywords: Pancreatic cancer; SBRT; Local recurrence
Local control and clinical outcomes of MR-guided SBRT for liver metastases and hepatocellular carcinoma: our institutional experience Beatriz Moreno Fuentes 1 , Inmaculada Navarro Domenech 1 , Beatriz Deben Mendez 1 , Marta Rodriguez Roldan 1 , Marta Mendez Rodriguez 1 , Marta Rodriguez Pertierra 1 , Raul Matute Martin 1 , Carlos Ferrer Gracia 2 , Rosa Maria Morera Lopez 1 1 Radiation Oncologist, Hospital Universitario La Paz, Madrid, Spain. 2 Radiophysics and radiation protection, Hospital Universitario La Paz, Madrid, Spain Purpose/Objective: To evaluate local control (LC) and clinical outcomes in patients with liver metastases or hepatocellular carcinoma (HCC) treated with magnetic resonance- guided stereotactic body radiotherapy (MR-linac SBRT). Feasibility, safety, efficacy, and the effect of daily online adaptive planning were analyzed. Material/Methods: We retrospectively analyzed 41 patients treated with MR-linac SBRT (1.5T Elekta Unity) at our institution. Prescribed doses ranged from 24–50 Gy in 1–5 fractions every other day (mean BED ₁₀ : 98.0 Gy). Online adaptive replanning was performed for 100% of fractions. Endpoints included local control (LC), overall survival (OS), and adverse events (CTCAE v5.0). Kaplan–Meier curves and log-rank tests were used for
analysis. Results:
A total of 47 hepatic lesions were treated between February 2023 and January 2025: 39 metastases (predominantly colorectal [45.5%], renal [15.2%], and pancreatic [9.1%] origin) and 8 HCC. With a median follow-up of 17 months, the 1-year LC rate was 82.9%, and OS was 63.4%. In the HCC subgroup, LC was 87.5%, while in the metastases subgroup it was 66.7%. Grade 1 acute side effects occurred in 46.3% of patients, with asthenia and nausea being the most common symptoms; no grade ≥ 2 side effects were observed. Conclusion: A total of 47 hepatic lesions were treated between February 2023 and January 2025: 39 metastases (predominantly colorectal [45.5%], renal [15.2%], and pancreatic [9.1%] origin) and 8 HCC. With a median follow-up of 17 months, the 1-year LC rate was 82.9%, and OS was 63.4%. In the HCC subgroup, LC was 87.5%, while in the metastases subgroup it was 66.7%. Grade 1 acute side effects occurred in 46.3% of patients, with asthenia and nausea being the most common symptoms; no grade ≥ 2 side effects were observed. References: Rudra S, Jiang N, Rosenberg SA, et al. Online adaptive
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