Adaptive response and dose-response plateaus for initiation in a state-vector model of carcinogenesis

Purpose: To investigate whether it is possible to explain dose response pla teaus for in-vitro X-ray irradiation of different cell lines with radioprot ective mechanisms such as radiologically induced expression of scavengers a nd repair enzymes. Materials and methods: A biomathematical model was developed based on a pre vious state-vector model. New features of the model are a mathematical desc ription of enhanced repair and radical scavenging as a result of irradiatio n. Results: The model produces a plateau in the dose-response for in-vitro tra nformations between 0.5 and 1 Gy and for chromosome aberrations and it pred icts an inverse-fractionation effect within a selected range of doses. Conclusions: Adaptive response mechanisms within a state-vector model provi de a coherent explanation of the dose-response characteristics for in-vitro transformations and chromosomal aberrations. These results suggest the nee d for new experimental studies described in the paper.