Inflammation and oxidatively induced DNA damage: A synergy leading to cancer development

Genetic changes are central to the development of cancer and endow the cancer cells with pro-survival characteristics. These include sustained proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, activating invasion and, ultimately, enabling metastasic potential. Tumor promotion and progression are dependent on secondary processes provided by cells of the tumor environment, for example, the cells of the immune system. Inflammation is widely accepted to lead to tumorigenesis, mainly due to the induction of oxidative stress, DNA damage and accumulation of resulting mutations. Inflammation also affects immune surveillance and responses to therapy and can be also induced by exogenous sources, such as exposure to chemicals or ionizing radiation (IR). There is extensive cross talk between immune cells that infiltrate tumors and cancer cells. This chapter outlines the synergy between inflammatory response and DNA damage that ultimately can lead to tumor development under specific conditions. Recognition of these mechanisms of tumor progression will increasingly affect the development of new efficient means to diagnose and treat human cancer earlier.