ESTRO 2024 - Abstract Book

S5259

Radiobiology - Normal tissue radiobiology

ESTRO 2024

Results:

The median dose of CBCT was measured between 17 to 21 mGy/ session. No difference between the two groups (radiosensitive pts vs. controls) is detected when the comparisons between the different irradiation conditions consider the radiosensitive and the control (radioresistant) together. No combined CBCT+2 Gy effect on H2AX and ATM foci values was observed on normal control cells (p=0,16). However, the kinetics of both biomarkers were found to be strongly dependent on the individual factor. (Figure 1). DSB may be significantly less recognized and/or repaired in cells from radiosensitive patients. We observed a significant increase in the residual DSB at 24h post irradiation for HNC patients and the radiosensitive cell line (p= 0,03) (Figure 2). These results were confirmed with the pATM foci with a significant increase of pATM foci at 24h post-irradiation in HNC pts (p= 0,0313) (Figure 2). For these pts, a priming CBCT dose (d) applied Δt min before the challenging dose of 2 Gy (D) may have a sublinear effect on the DNA repair mechanisms and potentially on observed health tissue toxicity.

Conclusion:

This study asks whether the imaging dose may affect the biological response to the challenging dose (2 Gy). Our results highlight the importance of individual and tissue factors in recognizing and repairing DSB for the use of CBCT during treatment by radiotherapy. The main limitation of this study is the small population size: the pilot study's results should be considered as a proof of concept and must be consolidated with larger cohorts.

Keywords: CBCT - DNA repair- toxicity

References:

Popotte C, Letellier R, Paul D, Waltener A, Guillochon N, Munier M, Retif P. Evaluation of a Scintillating Plastic Optical Fiber Device for Measuring kV-Cone Beam Computed Tomography Dose. Sensors (Basel). 2023 Sep 9;23(18):7778.

IVInomad: https://fibermetrix.com/wp-content/uploads/2023/08/Fiche_produit_IVI_FR.pdf

Berthel E, Pujo-Menjouet L, Le Reun E, Sonzogni L, Al-Choboq J, Chekroun A, Granzotto A, Devic C, Ferlazzo ML, Pereira S, Bourguignon M, Foray N. Toward an Early Diagnosis for Alzheimer's Disease Based on the Perinuclear Localization of the ATM Protein. Cells. 2023 Jun 29;12(13):1747.

Olivieri G, Bodycote J, Wolff S. Adaptive response of human lymphocytes to low concentrations of radioactive thymidine. Science. 1984 Feb 10;223(4636):594-7.

COPERNIC project investigators; Granzotto A, et al. Influence of Nucleoshuttling of the ATM Protein in the Healthy Tissues Response to Radiation Therapy: Toward a Molecular Classification of Human Radiosensitivity. Int J Radiat Oncol Biol Phys. 2016 Mar 1;94(3):450-60.

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Proffered Paper

Delineating the role of ATF4 in a preclinical model of radiation-induced myocardial fibrosis