Erythrocyte superoxide dismutase activity in patients with digest cancer: adjuvant diagnosis test

Previous studies showed that a common feature of tumor cells is their low of superoxide dismutase (SOD) activity. Our research proved that carcinogenic substances reduce erythrocyte SOD activity, while anticarcinogenic ones increase it and that in vitro SOD assessments revealed a direct mechanism of action. In this paper we determined erythrocyte SOD activity in patients with digestive and extra-digestive cancers. We studied eight groups of patients with five different forms of cancer (histopathologically confirmed) and three groups of volunteers. Group 1 (n = 86), patients with esophageal cancer; Group 2 (n = 94), patients with gastric cancer; Group 3 (n = 79), patients with colorectal cancer; Group 4 (n = 71), patients with hepatic cancer; Group 5 (n = 73), patients with pancreatic cancer; Group 6 (n = 85), patients with with other diseases, but of the same organs; Group 7 (n = 97), healthy volunteers; Group 8 (n = 91), hypertensive patients. We determined the erythrocyte SOD activity using the catecholamine oxidation method. Erythrocyte SOD from the first 5 groups had a mean value of 1.91 +/- 0.78 EU as compared with Group 6 which presented an activity of 6.08 +/- 1.02 (P < 0.001) and Group7 in which the activity was 6.54 +/- 1.23 (P < 0, 001). Erythrocyte SOD activity is significantly reduced (by 2-3 fold) in all groups of cancer patients studied. Being accessible, simple and rapid, erythrocyte SOD activity determination could constitute an adjuvant test in diagnosis of these types of cancer. Taking into account our previous results which prove that carcinogenic substances inhibit SOD activity by a direct mechanism, we suggest that further research is required in this exciting field.