It is necessary to consider, however, that changes in the ROS threshold by antioxidant compounds may differently affect the viability of tumor cells; for example, if we consider the literature on the biological effects of heme-oxygenase-1 (HO-1), we can observe that its upregulation can promote cell cycle arrest and cellular death in some tumors, whereas it has also been associated with tumor survival and progression in other neoplasms [34,35,36]. This evidence concerns the gene HMOX1 and neoplasm.