Decreased incidence of prostate cancer with selenium supplementation: results of a double-blind cancer prevention trial
Article first published online: 25 DEC 2001
British Journal of Urology
Volume 81, Issue 5, pages 730–734, May 1998
How to Cite
Clark, Dalkin, Krongrad, Combs Jr, Turnbull, Slate, Witherington, Herlong, Janosko, Carpenter, Borosso, Falk and Rounder (1998), Decreased incidence of prostate cancer with selenium supplementation: results of a double-blind cancer prevention trial. British Journal of Urology, 81: 730–734. doi: 10.1046/j.1464-410x.1998.00630.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
- Prostate cancer;
- cancer screening;
- trace minerals;
- clinical trials
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.
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.
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.