S1101
Clinical – Upper GI
ESTRO 2026
Results: Of 164 consecutive patients, 91 (55.5%) had distal oesophageal and 73 (44.5%) pancreatic primaries. Most presented with advanced disease: 90 (54.9%) stage III, 34 (20.7%) stage IV (including 11 oesophageal IVA [M0], 7 oesophageal IVB [M1], and 16 pancreatic [M1]), and 40 (24.4%) stage I–II. RT was delivered in the adjuvant setting in 52 cases (31.7%). At a median follow-up of 24 months, a total of 118 patients (72%) relapsed: 70 (42.7%) with LRR and 48 (29.3%) with distant-only progression, while 46 (28%) remained disease-free. Among those with LRR, Type C recurrences predominated (n = 62; 88.57%), with only 6 (8.57%) marginal and 2 (2.86%) extraneous failures.Pancreatic primaries accounted for 56.5% of central recurrences, whereas oesophageal cancers were more frequent among non-recurrent cases (78%). Advanced stage (III–IV) was associated with distant-only failure, while earlier stages correlated with local control. Marginal recurrences were observed in 3 of 18 adjuvant cases (16.7%) and 3 of 52 non-adjuvant cases (5.8%), a difference that did not reach statistical significance (OR= 0.31; p = 0.17).
radiotherapy for liver tumors on a 1.5 T MR-linac: initial clinical experience and workflow. Int J Radiat Oncol Biol Phys. 2019;105(4): 824 - 834.Finazzi T, Bol GH, van den Berg CA, et al. MR-guided stereotactic body radiotherapy of liver metastases: feasibility and early clinical results. Radiother Oncol. 2019;141:165 - 172.Weykamp F, Hoegen P, Regnery S, et al. Long - Term Clinical Results of MR - Guided Stereotactic Body Radiotherapy of Liver Metastases. Cancers (Basel). 2023;15(10):2786. doi:10.3390/cancers15102786. Keywords: MR-guided SBRT, Online adaptive radiotherapy patterns of failure and recurrence mapping after 4D-radiotherapy in upper gastrointestinal cancers (distal oesophageal and pancreatic cancers) Mohammad Emarah 1,2 , Katharine Aitken 1,3 , Brian Hin 1 , Amr A Elsaid 2 , Nashaat Lotfy 2 , Mohamed Abouegylah 2 , Alyaa Hosny 2 , Irene Chong 1,3 , Diana Tait 1,3 1 Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, London, United Kingdom. 2 Clinical Digital Poster 3368 Oncology Department, Alexandria University, Alexandria, Egypt. 3 Radiotherapy and imaging Department, The Institute of Cancer Research, London, United Kingdom Purpose/Objective: Loco-regional recurrence remains a common pattern of failure following radiotherapy (RT) for upper gastrointestinal malignancies. The use of four- dimensional (4D) CT permits individualisation of motion margins, typically resulting in smaller planning target volumes (PTVs) compared to 3D margins [1]. This study evaluated recurrence patterns relative to RT PTVs in distal oesophageal and pancreatic cancers treated with radical-dose 4D-RT to investigate
Conclusion: In this 4D-RT single UK-centre cohort, loco-regional recurrences occurred predominantly within the treated high-dose volume, indicating that geometric coverage with 4D-RT was generally sufficient. The predominance of central failures, particularly in pancreatic cancer, suggests a possible contribution of biological tumour factors to in-field relapse. Marginal and extraneous failures were uncommon and mainly observed when radiotherapy was given in the adjuvant setting. References: [1] Sangalli, G., Passoni, P., Cattaneo, G. M., Broggi, S., Bettinardi, V., Reni, M., … Calandrino, R. (2010). Planning design of locally advanced pancreatic carcinoma using 4DCT and IMRT/IGRT technologies. Acta Oncologica, 50(1), 72–80. https://doi.org/10.3109/0284186X.2010.484425 Keywords: GI cancer, recurrence, 4D radiotherapy
marginal failure rates. Material/Methods:
We retrospectively analysed consecutive patients with distal oesophageal or pancreatic cancers treated with radical-dose 4D-RT, including selected M1 stage IV patients treated for limited metastatic burden, between January 2017 and December 2020.First recurrence sites were classified as local (primary), nodal (regional), distant (metastatic), or combinations thereof. For patients with loco-regional recurrence (LRR), the recurrence centre was mapped relative to the PTV and categorised as Type C (central, within PTV), Type M (marginal, ≤ 1 cm outside PTV), or Type E (extraneous, >1 cm beyond PTV). Each patient was assigned to a single hierarchical category (Type C, M, E, distant-only, or no recurrence).
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