HDAC9 and neoplasm: With deepening research, it was observed that some epigenetic modifiers can be used as radiation sensitizers, such as histone deacetylase(HDAC) inhibitors, DNA methyltransferase (DNMT) inhibitors, EZH2 inhibitors BET inhibitors, etc. They can destroy DNA-damage repair and cell cycle and increase oxidative stress to enhance the anti-tumor activity of radiotherapy [5].