ESTRO 2024 - Abstract Book

S150 ESTRO 2024 degenerative syndromes like Alzheimer’s disease. Notwithstanding their clinical consequences, what is the radiobiological rationale of such LDRT? By considering the antagonist phenomena specific to low doses like hormesis or hypersensitivity to low dose (HRS) and the role of the ATM protein in the individual response to radiation, we will present the biological relevance of the radiation-induced ATM nucleoshuttling (RIANS) model for LDRT and highlight the non-linear dose-effects that can occur in certain low dose ranges. After low doses (less than 1 Gy), the number of radiation-induced DNA strand breaks is low but the diffusion of ATM monomerized by radiation from the cytoplasm to the nucleus may be sufficient to recognize DNA strand breaks, to protect normal cell tissues and trigger anti-inflammatory process :such very specific conditions can be considered as an hormetic effect. By contrast, in other conditions (other dose range, dose-rate, tissue type), if the number of ATM proteins present in the nucleus early after irradiation is not sufficient, the lack of recognition and repair of DNA strand breaks may lead to cell death and radiobiological features similar to 5-10 times higher doses : this is the case of the HRS phenomenon. After low doses (less than 1 Gy), the number of radiation-induced DNA strand breaks is low but the diffusion of ATM monomerized by radiation from the cytoplasm to the nucleus may be sufficient to recognize DNA strand breaks, to protect normal cell tissues and trigger anti-inflammatory process :such very specific conditions can be considered as an hormetic effect. By contrast, in other conditions (other dose range, dose-rate, tissue type), if the number of ATM proteins present in the nucleus early after irradiation is not sufficient, the lack of recognition and repair of DNA strand breaks may lead to cell death and radiobiological features similar to 5-10 times higher doses : this is the case of the HRS phenomenon. Invited Speaker

To go further : Le Reun E, Foray N.Cancers (Basel). 2023 Feb 26;15(5):1482.

doi: 10.3390/cancers15051482.