Molecular analyses of adaptive survival responses (ASRs): role of ASRs in radiotherapy.

Adaptive survival responses (ASRs), whereby cells demonstrate a survival advantage when exposed to very low doses of ionizing radiation (IR) 4 - 24 h prior to a high dose challenge, were first reported over 15 years ago. These responses were linked to hormesis, which implied that exposure to low levels of IR may be beneficial to the cell. We postulate that increased survival does not necessarily mean that the treatment is beneficial.