ESTRO 2024 - Abstract Book

S2242

Clinical - Upper GI

ESTRO 2024

Keywords: Proton, Hepatocellular carcinoma, Radiotherapy

2288

Digital Poster

Hypo-fractionated proton RT for locally advanced pancreatic cancer: technique and initial outcomes.

Sofia Paola Bianchi 1,2 , Antonio Carlino 3 , Slavisa Tubin 2 , Markus Stock 3 , Giovanna Martino 3 , Eugen Hug 2 , Piero Fossati 2,4 1 University of Milano Bicocca, School of medicine and Surgery, Milano, Italy. 2 MedAustron Ion Therapy Center, Radiation Oncology Department, Wiener Neustadt, Austria. 3 MedAustron Ion Therapy Center, Medical Physics Department, Wiener Neustadt, Austria. 4 Karl Landsteiner, University of Health Sciences, Krems an der Donau, Austria

Purpose/Objective:

In Locally Advanced Pancreatic Carcinoma (LAPC) the role of radiotherapy is well-recognized in operable and borderline resectable pancreatic cancer, supported by the results from the Preopanc trial. The role of Stereotactic Body Radiation Therapy (SBRT) is not as firmly established; however, encouraging data from photon-based therapy in neoadjuvant or radical settings demonstrated a favorable impact on the rate of R0 resections, which are associated with improved long-term prognosis. This study aims to provide insights into the treatment technique and preliminary outcomes of hypo-fractionated, highly conformal Proton Radiotherapy (PRT) for LAPC.

Material/Methods:

From January 2019 to May 2021, ten patients affected by non-metastatic, non-resectable LAPC were treated with a Simultaneous Integrated Boost (SIB) approach, consisting in the administration of 37.5 Gy[RBE] (n=6) or 40 Gy[RBE] (n=4) to the macroscopic disease, and 25 Gy[RBE] to the locoregional lymph nodes and the neuro plexus, according to the guidelines of the Japanese Pancreas Society (JPS) Classification, in a total of 5 fractions. The most critical dose constraint was D0.1cc <35 Gy[RBE] for duodenum (Figure1). Abdominal compression, 4DCT planning and rescanning were used to minimize the impact of organ motion. Robustness was improved using PRVs for OARs. Robustness was verified with plan recalculation on control 4D-CT. Lymphocyte levels were assessed before and after PRT, and CA19.9 levels one month after PRT were compared with the baseline values. Treatment-related adverse events were measured with Common Terminology Criteria for Adverse Events (CTCAE v5.0) Local Recurrence (LR), Overall Survival (OS), and Freedom From Distant Metastasis (FFDM) were calculated by performing Kaplan-Meier analysis from the end of PRT.