A secondary analysis of the SELECT trial demonstrated no significant difference in bladder cancer incidence with selenium supplementation compared with placebo (HR, 1.13; 95% CI, 0.70-1.84).9 A randomized, double-blind phase 3 trial also found no significant difference in noninvasive bladder cancer recurrence with selenium supplementation (200 µg/day high-selenium yeast) compared with placebo (HR, 0.85; 95% CI, 0.56-1.29).10
An analysis of the Nutritional Prevention of Cancer Trial, which included an additional 3 years of follow-up beyond the blinded trial period, found no significant difference in overall lung cancer incidence with selenium supplementation compared with placebo.11 Though selenium supplementation did result in significantly lower lung cancer incidence among patients with low baseline serum selenium levels compared with placebo (HR, 0.42; 95% CI, 0.18-1.96; P = .04).
Combined supplementation with selenium, α-tocopherol, and β-carotene, however, did not affect lung cancer incidence compared with placebo in a randomized controlled trial conducted in China.12
Several studies showed no difference in the overall incidence of basal or squamous cell carcinoma of the skin with selenium supplementation compared with placebo.13 Though 1 of the double-blind, randomized, controlled trial found an increased risk of squamous cell carcinoma (HR, 1.25; 95% CI, 1.03-1.51) and total nonmelanoma skin cancer (HR, 1.17; 95% CI, 1.02-1.34), but not basal cell carcinoma, compared with placebo.14,15 Another trial, the SU.VI.MAX study of 12,741 subjects aged 35 to 60, also found an increased risk of skin cancer among women, but not men, which resolved during the post-intervention period (ie, selenium supplementation was discontinued).16
The Selenium and Celcoxib (Sel/Cel) Trial randomly assigned 1621 patients aged 40 to 80 after colonoscopic removal of colorectal adenoma(s) to receive selenium (200 µg/day as selenized yeast) and/or celecoxib (400 mg/day), or placebo.17 There was no significant difference in the overall incidence of recurrent colorectal adenomas between arms. Selenium supplementation among patients with advanced adenomas at baseline, however, had a significantly lower rate of recurrence compared with placebo (RR, 0.82; 95% CI, 0.71-0.96; P = .01).
Most studies found effect of selenium supplementation on decreasing the incidence of certain cancers, though the data are mixed.
Some analyses from The Nutritional Prevention of Cancer Trial, however, suggest that patients with low baseline selenium levels may benefit from selenium supplementation. Other data suggest, however, that selenium supplementation may increase the risk of basal or squamous cell carcinoma recurrence, particularly among women.
- Selenium. Dietary supplement fact sheet. National Institutes of Health. Updated 2016. https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/. Accessed August 28, 2017.
- Hurst R, Hooper L, Norat T, et al. Selenium and prostate cancer: systematic review and meta-analysis. Am J Clin Nutr. 2012;96(1):111-122. doi: 10.3945/ajcn.111.033373
- Cai X, Wang C, Yu W, et al. Selenium exposure and cancer risk: an updated meta-analysis and meta-regression. Sci Rep. 2016;6:19213. doi: 10.1038/srep19213
- Jiang L, Yang KH, Tian JH, et al. Efficacy of antioxidant vitamins and selenium supplement in prostate cancer prevention: a meta-analysis of randomized controlled trials. Nutr Cancer. 2010;62(6):719-727.doi: 10.1080/01635581.2010.494335
- Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39-51. doi: 10.1001/jama.2008.864
- Marshall JR, Tangen CM, Sakr WA, et al. Phase III trial of selenium to prevent prostate cancer in men with high-grade prostatic iintraepithelial neoplasia: SWOG S9917. Cancer Prev Res (Phila). 2011;4(11):1761-1769. doi: 10.1158/1940-6207
- Stratton MS, Algotar AM, Ranger-Moore J, et al. Oral selenium supplementation has no effect on PSA velocity in men undergoing active surveillance for localized prostate cancer. Cancer Prev Res (Phila). 2010;3(8):1035-1043. doi: 10.1158/1940-6207.CAPR-09-0143
- Duffield-Lillico AJ, Dalkin BL, Reid ME, et al. Selenium supplementation, baseline plasma selenium status and incidence of prostate cancer: an analysis of the complete treatment period of the Nutritional Prevention of Cancer Trial. BJU Int. 2003;91(7):608-612. doi: 10.1046/j.1464-410X.2003.04167.x
- Lotan Y, Goodman PJ, Youssef RF, et al. Evaluation of Vitamin E and Selenium Supplementation for the Prevention of Bladder Cancer in SWOG Coordinated SELECT. J Urol. 2012;187:2005-2010. doi: 10.1016/j.juro.2012.01.117
- Goossens ME, Zeegers MP, van Poppel H, et al. Phase III randomised chemoprevention study with selenium on the recurrence of non-invasive urothelial carcinoma. The SELEnium and BLAdder cancer Trial. Eur J Cancer. 2016;69:9-18. doi: 10.1016/j.ejca.2016.09.021
- Reid ME, Duffield-Lillico AJ, Garland L, Turnbull BW, Clark LC, Marshall JR. Selenium supplementation and lung cancer incidence: an update of the nutritional prevention of cancer trial. Cancer Epidemiol Biomarkers Prev. 2002;11(11):1285-1291.
- Kamangar F, Qiao YL, Yu B, et al. Lung cancer chemoprevention: a randomized, double-blind trial in Linxian, China. Cancer Epidemiol Biomarkers Prev. 2006;15:1562-1564. doi: 10.1158/1055-9965.EPI-06-0316
- Pais R, Dumitraşcu DL. Do antioxidants prevent colorectal cancer? A meta-analysis. Rom J Intern Med. 2013;51(3-4):152-163.
- Clark LC, Combs GF Jr, Turnbull BW, et al. Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial. Nutritional Prevention of Cancer Study Group. JAMA. 1996;276(24):1957-1963.
- Duffield-Lillico AJ, Slate EH, Reid ME, et al. Selenium supplementation and secondary prevention of nonmelanoma skin cancer in a randomized trial. J Natl Cancer Inst. 2003;95:1477-1481.
- Ezzedine K, Latreille J, Kesse-Guyot E, et al. Incidence of skin cancers during 5-year follow-up after stopping antioxidant vitamins and mineral supplementation. Eur J Cancer. 2010;46:3316-3322. doi: 10.1016/j.ejca.2010.06.008.
- Thompson PA, Ashbeck EL, Roe DJ, et al. Selenium supplementation for prevention of colorectal adenomas and risk of associated type 2 diabetes. JNCI J Natl Cancer Inst. 2016;108:djw152. doi: 10.1093/jnci/djw152