The role of hypoxia in radiation response

© Springer International Publishing Switzerland 2016. Radiation is a very effective form of cancer therapy but its effectiveness is significantly influenced by changes in the levels of oxygen, nutrients and pH in the tumor microenvironment. Radiation dose is also limited by normal tissue toxicity, which can manifest itself both in early effects as well as in late effects. Therefore, approaches aimed at improving the therapeutic window for radiotherapy should consider both the effects of the tumor microenvironment such as hypoxia, and also target pathways that may reduce radiation-induced normal tissue toxicity. With these concepts in mind, we review the biological consequences of tumor hypoxia and the effects of hypoxia/HIF on tumor radiation sensitivity as well as the effects of targeting the HIF/PHD axis for normal tissue radioprotection.