ESTRO 2024 - Abstract Book

S5328

Radiobiology - Tumour biology

ESTRO 2024

Radiation induced NRF2 expression and upregulated total antioxidant capacity, which may compromise the effect of RT-induced ROS. Changes in serum total antioxidant capacity during RT could serve as a novel predictor of treatment outcome in HNSCC patients.

Keywords: Antioxidants, NF-E2-Related Factor 2, HNSCC

References:

Medical Ethics Review Committee (CMO) approval - CMO number: 2007/104

408

Proffered Paper

Comparison of the effectiveness of photon and proton irradiations in a hypoxic rat prostate tumor

Michaela Schmitt 1,2,3 , Christin Glowa 1,3,4 , Peter Peschke 1,3 , Stephan Brons 3,5 , Christian P. Karger 1,3

1 German Cancer Research Center (DKFZ), Division of Medical Physics in Radiation Oncology, Heidelberg, Germany. 2 Heidelberg University, Faculty of Biosciences, Heidelberg, Germany. 3 National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany. 4 Heidelberg University Hospital, Department of Radiation Oncology and Radiotherapy, Heidelberg, Germany. 5 Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg, Germany

Purpose/Objective:

In vitro studies indicate that proton irradiations not only exhibit an increased relative biological effectiveness (RBE) but also lower oxygen enhancement ratio (OER) as compared to photons [1]. To assess the potential of proton radiotherapy in hypoxic tumors in vivo , the rat prostate adenocarcinoma Dunning R3327-HI was used to investigate the dose response of photon and proton irradiation under oxic and hypoxic conditions. In addition, the potential influence on the tumor microenvironment and the immune system under oxic condition was investigated in a time dependent manner since radiation response is not limited to the tumor cells, but also involves the tumor microenvironment and immune system.

Material/Methods:

The HI tumor is characterized by moderate differentiation, a tumor volume doubling time of approximately 10 days and moderate chronic hypoxic areas. A fragment of a donor tumor was implanted subcutaneously in the right hind thigh of male Copenhagen rats. When the tumors reached a mean diameter of 10 mm, they were randomized and irradiated with either 6 MV photons of a clinical linear accelerator or protons at the Heidelberg Ion Beam Therapy