SOD1 and neoplasm: In agreement with other studies, different used treatment regimens especially the combination therapy significantly increase ROS levels which leads to oxidative damage to cellular structures and decreases antioxidant enzymes SOD and CAT activity in tumor tissue compared with the SEC group [44] as SOD catalyzes the dismutation of superoxide anion (O2−) to H2O2 and O2 [45]; also, CAT enzyme reduces H2O2 to H2O [43].