Prognostic significance of serum superoxide dismutase activity in patients with gastric cancer

Background. Although superoxide dismutase (SOD) may play an important role in helping to protect against carcinogenesis or tumor progression, little information is available regarding the clinical evaluation of antioxidant defense in patients with gastric cancer. Methods. Serum SOD activity in 34 patients with gastric cancer was estimated and the data compared with clinicopathological parameters. Results. The mean serum SOD activity in the patients was 15.9% ± 2.6%, which was higher than the value obtained in healthy donors. The serum SOD activity in patients over 70 years of age was 14.5% ± 3.0%, which was significantly lower than the value of 16.6% ± 7.3% in those under 70 years of age (P < 0.01). According to the stage of disease, the reduction in SOD activity in the patients aged over 70 years was significant in those with far advanced tumor, classified as stage IV (P < 0.01), but not in those with stage I-III disease. When the cutoff value for high- and low-SOD groups was determined as 18.0%, based on the median value for serum SOD activity in 15 patients with stage IV gastric cancer, the survival rate of patients with stage IV tumor was significantly higher in the high-SOD group than in the low-SOD group (P < 0.05). Conclusion. These findings suggested that the reduction in serum SOD activity in elderly patients may be due to weakness of the antioxidant defense of the host, thus resulting in a poor prognosis in those with far-advanced (stage IV) gastric cancer.