Mortality rates from cancer or all causes and SOD activity level and Zn/Cu ratio in peripheral blood: Population-based follow-up study

A total of 507 residents (232 males and 275 females) of a rural area of Hokkaido, Japan, were enrolled in the present follow-up study as the follow-up cohort. We investigated the relationship between mortality rates from cancer or all causes and blood levels of SOD activity and Zn/Cu ratio, and serum levels of SOD activity and lipid peroxides (TBARS), by following up our subjects over the course of 18 years. The hazard ratios of lowest blood levels of SOD activity and Zn/Cu ratios to mortality rates from cancer were 1.36 (95% C.I., 0.59-3.10) and 1.97 (95% C.I., 0.84-4.63), and those to mortality rates from all causes were 1.31 (95% C.I: 0.76-2.27) and 1.99 (95% C.I.: 1.14-3.46), respectively, in comparison with subjects with highest values for these factors. Hazard ratios of lowest serum levels of SOD activity and TBARS to mortality rates from cancer were 2.68 (95% C.I., 1.05-6.82) and 0.71 (95% C.I.: 0.31-1.67), and those to mortality rates from all causes were 1.55 (95% C.I., 0.90-2.66) and 0.88 (95% C.I.: 0.51-1.50), respectively. The results of this follow-up study indicate that high serum SOD activity is associated with protective effects against mortality from cancer, and that high blood Zn/Cu ratio is associated with low mortality from other causes. In contrast, serum TBARS levels do not appear to be a biomarker for the risk of death from cancer.