FIGURE 1.

DNA damage causes cancer development when erroneous DNA repair leads to mutations of chromosomal aberration that activate oncogenes or inactivate tumor suppressors genes (red). When DNA damage persists and interferes with replication or transcription, DNA damage checkpoints trigger cellular senescence or apoptosis that inactivate or eliminate damaged cells and thus suppress tumorigenesis (gray). DNA repair mechanisms prevent cancer by preventing mutations. Chemo- and radiotherapy often inflict DNA damage to halt cancer cell proliferation or trigger the apoptotic demise of cancer cells.