VEGFA and cancer: Radiation-induced secretion of VEGF, FGF, and PDGF by cancers protects the cancer vasculature from radiation-mediated cytotoxicity and enhances the radioresistance of ECs.386–388 Thus, VEGF, FGF, and PDGF inhibitors can significantly improve the efficiency of radiotherapy.388,389 The radiosensitivity of hypoxic cancer cells was showed to be significantly increased after reoxygenation.390 Elevated H2O2 levels in cancer tissues exacerbate hypoxia-induced resistance to radiotherapy.