SOD2 increased in many tumor types as they progress from early stage non-invasive disease to late stage metastatic disease, and its over-expression in many instances enhance the metastasis phenotype because SOD2 is able to catalize toxic oxidant O2.- into another toxic oxidant H2O2 and hydroperoxides, and O2.- and H2O2 / hydroperoxides both directly contribute to oxidative stress. This evidence concerns the gene SOD2 and neoplasm.