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

Abstract

Purpose: To investigate whether it is possible to explain doseresponse plateaus for in-vitro X-ray irradiation of different cell lines with radioprotective mechanisms such as radiologically induced expression of scavengers and repair enzymes. Materials and methods: A biomathematical model was developed based on a previous state-vector model. New features of the model are a mathematical description of enhanced repair and radical scavenging as a result of irradiation. Results: The model produces a plateau in the dose-response for in-vitro tranformations between 0.5 and 1Gy and for chromosome aberrations and it predicts an inverse-fractionation effect within a selected range of doses. Conclusions: Adaptive response mechanisms within a state-vector model provide a coherent explanation of the dose-response characteristics for in-vitro transformations and chromosomal aberrations. These results suggest the need for new experimental studies described in the paper.