S1097
Clinical – Upper GI
ESTRO 2026
Recoletas Healthcare Segovia, Segovia, Spain. 10 Radiation Oncology Department, Recoletas Salud Campo Grande Hospital, Valladolid, Spain. 11 Radiation Oncology Department, Badajoz University Hospital, Badajoz, Spain. 12 Biomedical Engineering and Telemedicine Centre, ETSI Telecomunicación, Universidad Politécnica de Madrid, Madrid, Spain. 13 Radiation Oncology Department, HM Hospitales, Madrid, Spain Purpose/Objective: Stereotactic Body Radiotherapy (SBRT) for liver metastases (LM) achieves excellent local control, but early distant progression (EDP) limits survival. EDP within 6 months suggests inappropriate patient selection for local therapy. Identifying patients at high risk of EDP before SBRT is a critical unmet need. The objective of this multicenter study was to identify robust predictive factors, clinical and dosimetric, for EDP in a cohort treated with SBRT for LM. Material/Methods: We performed a retrospective analysis of 79 patients (116 lesions) treated with SBRT for LM across 9 Spanish centers (2016-2025). Inclusion criteria included 1-3 LM, controlled primary tumor, and adequate liver function. The primary endpoint was EDP, defined as new distant metastatic disease on imaging within 6 months of SBRT completion. Clinical variables (primary histology [CRC vs. non-CRC], DFI, synchronous/metachronous status, number of LM) and dosimetric parameters (Total Dose, Dose/fraction, BED10, EQD2, GTV volume) were collected. Kaplan- Meier and Cox proportional-hazards regression were used for univariate (UVA) analysis. Results: Median age was 69 years (range 33-89). The predominant histology was colorectal (CRC) (60.8%). Median follow-up was 13.2 months. EDP (<6 months) occurred in 26 patients (33%). Median distant progression-free survival (DPFS) for the cohort was 8.9 months. 1-year local control was 92%. On UVA, factors significantly associated with increased EDP risk were dose per fraction (p=0.004), BED10 (p=0.05), and EQD2 (p=0.049). Notably, no clinical factors analyzed (histology, DFI, number of LM) were predictive.
on time was 12 minutes and 35 seconds (95%CI391.3- 884.7 seconds). Beam-hold occurred in all fractions with a mean of 55.4 instances (95%CI36-81). Thirty- nine baseline shift plans were performed due to persistent target drifts. At the last treatment session, adverse events assessed by CTCAE v5.0 were 9 cases of grade (G) 1 nausea, 7 G1 abdominal pain and 1 nausea G2. No hemorrhage and no ≥ G3 occurred. With a median follow-up of 8 months, no patient experienced late ≥ G2 side effects. One patient died and radiological response was observed in 74%. Extrapancreatic recurrence was main pattern of failure and median PFS was 3 months (range1-12). Conclusion: CMM was efficaciously implemented for pancreas MRgSBRT. This let to PTV margins reduction, decreasing the amount of healthy tissue within the high dose region and enabling high treatment precision. Treatment duration was minimally increased and the procedure was well tolerated. References: De-Colle C, Rigo M, Allegra AG, Nicosia L, Giaj-Levra N, Pastorello E, Ricchetti F, Orsatti C, Romei A, Bianchi N, Borgese RF, De Simone A, Gurrera D, Naccarato S, Sicignano G, Ruggieri R, Alongi F. The Clinical Feasibility and Safety of 1.5 T MR-Guided Daily Adapted Radiotherapy in 1000 Patients: A Real-World Large Experience of an Early-Adopter Center. Cancers (Basel). 2025 Jun 17;17(12):2012. doi: 10.3390/cancers17122012. PMID: 40563661; PMCID: PMC12191406. Keywords: pancreas, SBRT, MR-Linac Predictive factors for Early Distant Relapse in patients treated with SBRT in liver metastases: a multicenter study Carolina De la Pinta 1,2 , Laura Romero 1 , Marta Bonet 3 , Iñigo San Miguel 4 , Meilyn Medina 5 , Mónica Sanchez 6 , Marina Peña 7 , María Luisa Vázquez 8 , Karla Rossi 9 , Rocio Cantalapiedra 10 , Carmen Corral 11 , Maria Elena Hernando 12 , Ovidio Hernando 13 1 Radiation Oncology Department, Ramon y Cajal Hospital, Madrid, Spain. 2 Biomarkers and therapeutic target Group, IRYCIS, Madrid, Spain. 3 Department of Radiation Oncology, Arnau de Villanova University Hospital, Lleida, Spain. 4 Radiation Oncology Department, University Hospital of Salamanca, Salamanca, Spain. 5 Radiation Oncology Department, University Hospital of Virgen de las Nieves, Granada, Spain. 6 Radiation Oncology Department, Sant Joan Hospital, Alicante, Spain. 7 Radiation Oncology Digital Poster 3245 Department, Quiron Madrid Hospital, Madrid, Spain. 8 Radiation Oncology Department, Meixoeiro Hospital, Vigo, Spain. 9 Radiation Oncology Department,
Conclusion: One-third of patients selected for liver SBRT experienced systemic failure within 6 months. A lower
Made with FlippingBook - Share PDF online