Abstract: The dose-limiting factor of radiotherapy is injury found in normal surrounding tumor tissues. It is characterized by inflammation, fibrotic changes, necrosis and other pathological changes. Hypoxic microenvironment is induced in normal tissues received radiation exposure. Previous studies demonstrated radiation-induced hypoxia increased hypoxia inducible factor-lα (HIF-1α), vascular endothelial growth factor (VEGF) and transforming growth factor-β (TGF-β) and other cytokines. They promoted radiation-induced normal tissues injury by HIF-1α signaling pathways, oxidative stress reaction, macrophages and miRNAs. In this study, we reviewed the effect of radiationinduced hypoxic microenvironment on normal tissues injury after radiation exposure.

Key words: Radiation, Normal tissue injury, Hypoxia