Decreased Selenium Concentration and Glutathione Peroxidase Activity in Blood and Increase of These Parameters in Malignant Tissue of Lung Cancer Patients

Abstract

We studied the selenium (Se) concentration in whole blood and plasma, glutathione peroxidase (GSH-Px) activity in red blood cells and plasma, as well as both of these parameters in cancerous and tumor-free lung tissue of lung cancer patients. Blood samples were taken from 84 cancer patients and 61 healthy controls. Normal and neoplastic lung tissues were obtained from 57 patients at the time of surgery. Se concentrations in whole blood and plasma were lower by 23% (p < 0.001) in patients compared with controls. GSH-Px activity in red cells was lower by 20.2% (p < 0.004) and in plasma by 11.7% (p < 0.05) in patients than in the control group. On the other hand, the tumor Se level was higher by 66.6% (p < 0.0001) and GSH Px activity by 49.5% (p < 0.0001) than in adjacent tumor-free tissue. No differences in Se concentrations and GSH-Px activities were found between squamous cell carcinoma and adenocarcinoma nor among the clinical stages of the disease. In the whole blood and plasma of cancer patients significantly lower Se concentrations were found in smokers than in nonsmokers. Significantly lower Se concentrations were also found among cancer patients who were smokers compared with controls. These findings show that in the blood of cancer the antioxidant ability, as measured by Se and GSH-Px, is reduced significantly. The cause of increased Se and GSH-Px in the malignant part of the lung is not understood and requires further studies.

Antioxidant defense markers modulated by glutathione S-transferase genetic polymorphism: results of lung cancer case–control study

“…These findings are in agreement with a study on children with different types of malignancy that also revealed a significantly lower level of that trace element. Several studies among patients with different malignancies indicated a 5-35% decrease in Se level as compared with healthy controls [2,43].…”

Selenium Levels during the Course of Radiotherapy

“…The mechanism is still not clear but it has been suggested that cancer cells use antioxidants more effectively than healthy cells, thus depleting circulating levels of antioxidants. The low selenium level therefore is secondary to the existing disease, rather as a consequence than a cause of cancer [18,20,36,37]. This hypothesis would be supported by some trials in which decreased selenium levels mainly were found in patients with advanced, metastatic disease [3,16,32].…”

“…Decreased selenium concentrations compared to controls have been described for most malignancies such as head-and-neck cancer, colorectal and cervical cancer [16,20,22,37]. The mechanism is still not clear but it has been suggested that cancer cells use antioxidants more effectively than healthy cells, thus depleting circulating levels of antioxidants.…”

“…This subgroup mostly suffers from dietary problems and malnutrition caused by cancer or previous surgery [36]. In addition, tobacco smoking and alcoholism is reported to be associated with lowered selenium concentrations [37]. With this range of risk factors the head-and-neck cancer patients were not only among those with the lowest selenium concentrations but were also overproportionally represented regarding the critically low values.…”

“…Reduced blood selenium levels have been described for most malignancies [7,20,36,37] and a further decrease by antitumoral treatment is expected. Several studies focused on the effect of chemotherapy on the selenium concentration [32][33][34]; however, there is no data in the literature regarding the influence of radiotherapy.…”