Prostate cancer (PC) is the most common cancer in men and a leading cause of 
cancer death. Prostatic gland accumulates reasonably high amount of selenium 
(Se), the element that prevents the development of PC. It is hypothesized that 
some selenoproteins inhibit the transformation of normal prostate epithelium 
into neoplasm. We studied Se levels in whole blood, plasma and prostate of 32 PC 
and 40 benign prostate hyperplasia (BPH) patients and in the control group 
composed of 39 healthy subjects. The selenoenzyme glutathione peroxidase 
(GSH-Px) was also measured in the patients' red cells, plasma and prostate 
tissue. Se concentration in whole blood and plasma in both groups of patients 
was lower as compared with controls, while in prostate gland it was 
significantly higher in PC than in BPH patients and controls. Red cell GSH-Px 
activity was the same in PC patients and controls but significantly lower in BPH 
patients. Plasma GSH-Px activity was significantly lower in PC patients than in 
the control group, and prostate GSH-Px activity was significantly lower in PC 
patients as compared with BPH patients. Since Se has anticancer properties, it 
is very likely that its low level in blood may facilitate the development of 
cancer. A higher level of Se in prostate of PC patients has no influence on 
GSH-Px activity in the gland.