Decreased incidence of prostate cancer with selenium supplementation: results of a double‐blind cancer prevention trial

Abstract

Objective To test if supplemental dietary selenium is associated with changes in the incidence of prostate cancer. Patients and method A total of 974 men with a history of either a basal cell or squamous cell carcinoma were randomized to either a daily supplement of 200 μg of selenium or a placebo. Patients were treated for a mean of 4.5 years and followed for a mean of 6.5 years. Results Selenium treatment was associated with a significant (63%) reduction in the secondary endpoint of prostate cancer incidence during 1983–93. There were 13 prostate cancer cases in the selenium‐treated group and 35 cases in the placebo group (relative risk, RR=0.37, P=0.002). Restricting the analysis to the 843 patients with initially normal levels of prostate‐specific antigen (≤4 ng/mL), only four cases were diagnosed in the selenium‐treated group and 16 cases were diagnosed in the placebo group after a 2 year treatment lag, (RR=0.26 P=0.009). There were significant health benefits also for the other secondary endpoints of total cancer mortality, and the incidence of total, lung and colorectal cancer. There was no significant change in incidence for the primary endpoints of basal and squamous cell carcinoma of the skin. In light of these results, the ‘blinded’ phase of this trial was stopped early. Conclusions Although selenium shows no protective effects against the primary endpoint of squamous and basal cell carcinomas of the skin, the selenium‐treated group had substantial reductions in the incidence of prostate cancer, and total cancer incidence and mortality that demand further evaluation in well‐controlled prevention trials.

Association between the GCG polymorphism of the selenium dependent GPX1 gene and the risk of young onset prostate cancer

“…Two of them are based on the measurement of the long-term selenium intake using toe-nail clippings, 3,6 one is based on serum selenium measurements, 5 and one on selenium supplementation in a double-blinded study. 2 Three studies reported a reduction of risk for developing prostate cancer as the selenium level increased, suggesting that selenium can provide a two -three-fold protection against prostate cancer. One study showed an association only in smokers, 5 and one study failed to find any significant association between toe-nail selenium level and the risk of prostate cancer.…”

“…Clark and colleagues 2 found striking evidence that selenium supplementation protected men against prostate cancer in a randomised trial in the USA (OR: 0.35; CI: 0.18 -0.65). Another study has revealed an inverse association between advanced prostate cancer and toe-nail selenium levels, a surrogate marker of long-term selenium intake.…”

Age-stratified serum levels of isoflavones and proportion of equol producers in Japanese and Korean healthy men

“…1,2 In general, foods rich in saturated fat and calories are considered as promoters of prostate cancer, 3,4 whereas vegetables and fruits, including selenium, vitamins A, E, D and C, and isoflavones are inhibitors. [5][6][7][8] It is strongly suggested that the recent significant increase in the incidence of prostate cancer, as well as cardiovascular diseases and diabetes mellitus in Japan may be due to the increased habitual consumption of high-calories high-fat food. Nonetheless, the morbidity of prostate cancer among the Japanese is still significantly lower than among the Caucasian, African and Hispanic people.…”

Dietary selenium intake, aldehyde dehydrogenase‐2 and X‐ray repair cross‐complementing 1 genetic polymorphisms, and the risk of esophageal squamous cell carcinoma

“…In a randomized trial in a Western population, significantly lower total cancer incidence and mortality were observed among patients who received selenium compared with patients who did not receive selenium. 8,9 The intervention trials of selenium supplementation in Linxian, China, an area with a high incidence and mortality of esophageal cancer, also revealed reductions in the risk of esophageal cancer. 10,11 Selenium can modulate DNA methylation and cancer susceptibility, [12][13][14][15] and selenium deficiency may induce genetic damage and play an important role in carcinogenesis.…”