The superoxide anion, hydrogen peroxide, and hydroxyl radical are oxygen free radicals which arise in cell metabolism and which are toxic to cells, with an important role in carcinogenesis. The measurement of the oxygen free radical is a problem due to the instantaneously changing nature, and therefore the superoxide dismutase(SOD) is employed which act as an oxygen free radical scavenger. The authors quantitatively analyzed the SOD levels in normal uterine cervix epithelium, cervical intraepithelial neoplasia, and in invasive cervical cancer patients by the SOD-525R spectrophotometric assay and compared the results between each group with respect to prognostic variables such as stage of disease, cell typ~e, lymph node involvement, and SCC Ag(TA-4 Ag) levels. (continue...)