Selenium and oxidative stress in cancer patients

In order to determine impairments of free-radical processes in blood serum of 94 untreated cancer patients with various localization of the tumors (gastric cancer, colon cancer, breast and ovarian cancers, hemoblastoses) selenium levels and parameters of oxidative stress (the sum of nitric oxide metabolites (NOx), superoxide dismutase (Cu/ZnSOD) and malondialdehyde (MDA), and catalase activity) have been investigated. A comparative evaluation of the efficacy of the selenium-containing drug Selenase (sodium selenite pentahydrate) has been carried out in 40 patients with malignant liver disease and clinical signs of liver failure during the early postoperative period. The selenium levels in cancer patients were 73.0 ± 2.6 μg/L; this is 25-30% lower than the normal value (110-120 μg/L). Decreased levels of NOx were detected in all patients regardless of tumor localizations (22.1 ± 1.1 μM, versus the normal range of 28.4 ± 0.9 μM). Only patients with extensive malignant process in the liver had the NOx levels, which significantly exceeded the normal values (p < 0.001). The high level of NOx had a toxic effect on hepatocytes and caused metabolic disorders and inflammatory-necrotic changes in the liver. All examined patients had increased levels of SOD and MDA in normal values of catalase activity. The use of Selenase in postoperative patients with tumors of the liver increased selenium levels by 10-12%. This was accompanied by a decrease in the content of SOD and NOx, and earlier recovery of detoxification and synthetic liver function. These findings point to intensification of oxidative stress and metabolic disorders in the malignant process, which is the basis for prescription of metabolic correction therapy. © 2013 Pleiades Publishing, Ltd.