S1106
Clinical – Upper GI
ESTRO 2026
Conclusion: This preliminary analysis confirms our previously reported improvement in target coverage with CBCT- based oART for EC. ¹ However, no significant OOI dose differences were observed. Preliminary adverse effects rates are low. Final analysis upon trial completion will update these findings and further evaluate clinical and pathological response rates and quality of life data. References: 1. Bachmann N, et al. Cone-beam computed tomography–based online adaptive radiotherapy of esophageal cancer in the neoadjuvant setting: Dosimetric analysis, toxicity, and treatment response. Radiother Oncol. 2025;209:110981. doi:10.1016/j.radonc.2025.110981.2. Wu AJ, et al. Expert consensus contouring guidelines for intensity modulated radiation therapy in esophageal and gastroesophageal junction cancer. Int J Radiat Oncol Biol Phys. 2015;92(4):911-920. doi:10.1016/j.ijrobp.2015.03.030.2. Keywords: Esophagus, adaptive radiotherapy, prospective Proffered Paper 3740 Carbon ion radiotherapy in non-metastatic pancreatic cancer: final results of the prospective Phase 2 PACK-study (NCT04194268) Jakob Liermann 1,2 , Patrick Naumann 3 , Cornelia Jaekel 1 , Lukas Baumann 4 , Manuel Roehrich 5 , Felix H Englert 1 , Inga Jessen 1 , Bouchra Tawk 1,6 , Maximilian Knoll 1,6 , Filipa Baltazar 2,6 , Semi Harrabi 1,2 , Christoph Springfeld 7 , Christoph Michalski 8 , Uwe Haberkorn 9 , Andrea Mairani 2 , Amir Abdollahi 6 , Juergen Debus 1,6 , Klaus Herfarth 1,2 1 Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany. 2 Department of Radiation Oncology, Heidelberg Ion- Beam Therapy Center (HIT), Heidelberg, Germany. 3 Radiation Oncology, Xcare Group, Saarlouis, Germany. 4 Institute of Biostatistics, University of Heidelberg, Heidelberg, Germany. 5 Department of Nuclear Medicine, Mainz University Hospital, Mainz, Germany. 6 Clinical Coopeartion Unit Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany. 7 Department of Medical Oncology, Heidelberg University Hospital, Heidelberg, Germany. 8 Department of Surgery, Heidelberg University Hospital, Heidelberg, Germany. 9 Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany Purpose/Objective: Conventional chemoradiation of non-metastatic pancreatic cancer is controversially discussed. While local tumor control can be significantly improved
compared to chemotherapy alone, there appears to be no benefit on overall survival (OS). High-linear energy transfer (LET)-radiation such as carbon ion radiotherapy (CIRT) could improve radiation response rates through more direct DNA damage compared to photon radiation. Initial clinical results from Asia appear to confirm this hypothesis. Material/Methods: In this single-center prospective Phase 2 trial, 25 patients with locally advanced or locally recurrent pancreatic cancer were included. Cases with distant metastasis or extensive nodal metastasis were excluded. Tumor and duodenum had to be separately identifiable. Study treatment consisted of hypofractionated irradiation with 48 Gy (RBE) in daily single doses of 4 Gy (RBE) prescribed to the macroscopic tumor. CIRT was performed using an intensity-controlled rasterscanning system for beam application. Concurrent chemotherapy with Gemcitabine 300 mg/m2 was administered weekly. The objective was to investigate the feasibility and safety of CIRT in non-metastatic pancreatic cancer with respect to the 1-year OS rate, defined as time from study inclusion. 1y- and 2y-OS and -PFS were calculated using the Kaplan-Meier method, 95% confidence intervals are shown. Toxicity was evaluated using CTCAEv5.0. Results: Twenty-three patients were included in the final analysis after the last patient completed the 1y-Follow- up. The 1y- and 2y-OS rates were 78.3% [63.1%; 97.1%] and 58.7% [41.1%; 83.9%]. The median OS was 26.5 months as of October 2025. The 1y- and 2y-PFS rates were 26.1% [13.1%; 51.9%] and 11.6 % [3.5%; 38.4%] with a median PFS of 8.1 months. In total, 5 patients developed local tumor recurrence after CIRT (21.7%). Study treatment was well tolerated with only three treatment-related CTCAE grade 3 toxicities, including one case of abdominal pain, one upper gastrointestinal hemorrhage and one ureteric stricture. No treatment-related CTCAE grade 4-5 toxicities could be observed. Conclusion: Chemoradiation with carbon ions seems to be a highly promising treatment for non-metastatic pancreatic cancer patients with acceptable toxicity rates and OS rates exceeding those of historical data of conventional photon radiotherapy and/or chemotherapy. Distant metastasis remains the dominant treatment failure. A subsequent randomized Phase 3 trial should investigate OS superiority of CIRT compared to conventional chemoradiotherapy. Keywords: Carbon ion radiotherapy, LAPC, Hypofractionation
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