ESTRO 2025 - Abstract Book

S1822

Clinical – Upper GI

ESTRO 2025

3312

Digital Poster Is Less More in Pancreatic Cancer? Marta Bonet 1 , Ona Pallisé 2 , Priscila Bernard 1 , Lucía Tueros 1 , Pablo Muriel 3 , Helena Salvador 3 , Manuela Bemudez 1 , David González 1 , Elena García 1 , Virginia García 1 , Sara Vázquez 1 , José E Baquedano 1 , Moisés Mira 1 1 Radiation Oncology, Hospital Universitari Arnau de Vilanova, Lleida, Spain. 2 Medical Oncology, Hospital Universitari Arnau de Vilanova, Lleida, Spain. 3 General and Digestive Surgery, Hospital Universitari Arnau de Vilanova, Lleida, Spain Purpose/Objective: Duodenopancreatectomy is the only curative option for pancreatic head cancer (PC); however, many patients present with lymph node involvement (pN1) and/or positive resection margins (R1), which worsen prognosis. Additionally, some patients are deemed unresectable due to vascular involvement. Given the ongoing debate around the role of radiotherapy (RT), this study evaluates the outcomes of patients treated with modern RT techniques at our institution in these challenging cases. Material/Methods: We retrospectively analyzed data on PC patients treated with RT following neoadjuvant chemotherapy, with or without subsequent surgery, between 2016 and 2023. Tumor characteristics were described, and outcomes— including relapse-free survival, progression-free survival, and overall survival—were compared between two groups: patients who received adjuvant RT (ART) in the pN+ and/or R1 setting, and those with unresectable disease treated with radical RT. Results: Between June 1, 2016, and December 31, 2023, 53 patients with PC received RT: 20 adjuvant, 26 radical, 6 palliative, and 1 SBRT. Among the 46 patients treated with ART(n=20) or radical RT(n=26) (table 1), median age was 65.5 years. The histology was adenocarcinoma in all cases, except for one undifferentiated carcinoma and one mucinous carcinoid. RT was administered concurrent to capecitabine. As shown in Figure 1, after a median follow-up of 21 months, no significant differences were observed in median survival (23 months for adjuvant RT vs. 21 months for radical RT), or in OS at 6, 12, 24, and 36 months (100%, 90%, 47.6%, and 23.8% for adjuvant RT vs. 92%, 80%, 40%, and 25% for radical RT), with a hazard ratio (HR) of 1.16 (95% CI: 0.55–2.37, p=0.670). Median time to relapse with ART was 13 months (range 10 - 20, 95% CI), while with radical treatment (non-resected patients), progression occurred with a median of 14 months (range 10 - 18, 95% CI). Progression-free survival rates were 86.7% and 53.3% for patients treated with ART at 6 and 12 months respectively, compared to 93.3% and 60% for unresectable patients. These differences were not statistically significant (HR 1.14, 95% CI 0.55-2.37, p=0.727).