ESTRO 2025 - Abstract Book

S1861

Clinical – Upper GI

ESTRO 2025

Conclusion: In this single institution planning study, SMART to abdominal targets resulted in mean absolute stomach NTCP reduction of 5.42% with 1 in 10 patients (1 in 7 delivered fractions) achieving a clinically meaningful NTCP benefit with daily adaptation.

Keywords: MR-g SABR, abdominal SABR, toxicity prediction

References: 1. Palma DA Stereotactic Ablative Radiotherapy for the Comprehensive Treatment of Oligometastatic Cancers: Long Term Results of the SABR-COMET Phase II Randomized Trial. J Clin Oncol. 2020 Sep 1;38(25):2830-2838. 2. Harrow S Stereotactic Radiation for the Comprehensive Treatment of Oligometastases (SABR-COMET): Extended Long-Term Outcomes. Int J Radiat Oncol Biol Phys. 2022 Nov 15;114(4):611-616. 3. Chen H Impact of daily plan adaptation on organ-at-risk normal tissue complication probability for adrenal lesions undergoing stereotactic ablative radiation therapy. Radiother Oncol. 2021 Oct;163:14-20.

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Digital Poster SBRT in elderly patients with pancreatic cancer: outcomes and toxicity Gian Marco Petrianni 1 , Michele Fiore 2,1 , Elena Onorati 2 , Gabriele D'Ercole 1 , Pasquale Trecca 1 , Edy Ippolito 2,1 , Sara Ramella 2,1 1 Radiation Oncology, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy. 2 Radiation Oncology, Università Campus Bio-Medico, Rome, Italy Purpose/Objective: Pancreatic cancer has a poor prognosis and is often diagnosed in elderly patients who may not be candidates for surgery or chemoradiation due to age and comorbidities. Stereotactic body radiotherapy (SBRT) offers a novel approach for treating pancreatic cancer by delivering precise, high-dose radiation in a few fractions to a limited target volume. This study aims to evaluate the efficacy and safety of SBRT in elderly patients with pancreatic cancer. Material/Methods: All patients included in this study cohort had a histologically confirmed diagnosis of pancreatic cancer. SBRT with volumetric modulated arc therapy (VMAT) was administered in three dose schedules based on the tolerance of adjacent normal tissues: 30 Gy in 5 fractions, 35 Gy in 5 fractions, 40 Gy in 5 fractions, and 45 Gy in 5 fractions. Data were collected retrospectively, and statistical analysis was conducted for progression-free survival (PFS), local progression-free survival (LPFS), metastasis-free survival (MFS), and overall survival (OS) using the Statistical Package for Social Sciences (SPSS, version 27; SPSS Inc., Chicago, IL, USA). The primary outcome was local control as assessed by CT scan. Acute and late toxicities were graded according to the Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. Results: The study population included 33 patients (11 men, 22 women) with a mean age of 77 years (range, 65–90), enrolled between July 2018 and May 2024. At diagnosis, pancreatic disease was considered resectable or borderline resectable in thirty patients (90.9%) and unresectable in three patients (9.1%). The median follow-up was 9.5 months (range, 4– 37.2 months). For the 33 patients who received SBRT, the median PFS was 29.6 months, with 1-year, 2-year, and 3 year PFS rates of 79%, 64% and 25%, respectively. The 1-year, 2-year, and 3-year LPFS rates were 88%, 73% and 54%, respectively (median LPFS not reached). Median MFS was 32.6 months, with 1-year, 2-year, and 3-year MFS rates of 90%, 80% and 48%, respectively. Median OS was 24.1 months, with 1-year, 2-year, and 3-year OS rates of 75.8%, 50%