New Meta-Analysis: Serum Selenium Levels and Prostate Cancer Risk

Study Take Away: This meta-analysis suggests that there is an inverse relationship between serum selenium levels and subsequent prostate cancer risk.

Introduction

Worldwide prostate cancer accounts for 25% of all cancers in men. The most iStock_000026317149Small.jpgrecent tally in 2015 says that one million new cases are added each year. Since 1996, scientists have studies the inverse relationship between geographic soil selenium levels and cancer mortality.1 In the decades that followed other studies supported the connection between serum selenium and prostate cancer risk.2,3,4

This recently published meta-analysis in Medicine journal (open access, MOOSE compliant study) on serum selenium and prostate cancer reviewed PubMed, Embase, Medline, and the Cochrane Library literature up to September 2016. After reviewing 1352 studies, the researchers narrowed the field to 17 studies, which included 6136 prostate cancer cases and >34,901 controls or participants.

The researchers concluded the following:

“Our study shows that increased serum selenium is associated with a reduced risk of prostate cancer. Selenium is an antioxidant and anticarcinogen.5 It is also an important component of 3 major proteins: selenoprotein-P, glutathione peroxidase (GPx), and albumin. Within GPx, selenium is part of the most important antioxidant enzyme system that prevents cellular injury.6

“In addition, selenium inhibits the expression of some oncogenes and promotes apoptosis.7 Selenium is also part of the most important antioxidant enzyme system involved in preventing peroxidation of cells.8 Like vitamin E, selenium may be a superior scavenger of reactive nitrogen oxide species, and has the capacity to decrease inflammation.9 Selenium also inhibits cell proliferation and decreases cell cycle progression through the reduction of cyclin in prostate cancer cell lines.10” See Figure 1 below for more on the study results.

 Why this study is significant:

  1. It was comprehensive as it included all relevant studies.
  2. This meta-analysis has a large sample size, which enhances the “statistical power,” thus lending reliability of the results.
  3. There was a significant inverse relationship between serum selenium levels and prostate cancer risk.
  4. Since serum selenium is a broad indicator of selenium in the diet, the study supports previous research showing that increased selenium intake may help prevent the development of prostate cancer.

FIGURE 1 Serum Selenium and Prostate Cancer Meta-Analysis 

 serum selenium_prostatecancer.jpeg

Conclusion: The study researchers supports “the hypothesis that there is a relationship between serum selenium levels and prostate cancer risk in populations with long-term steady selenium intake."

The researchers called for more well-designed cohort studies and randomized controlled studies based on non-Western populations because the study participants where heterogenus (United States, Denmark, Sweden, Iran, Finland). They also suggested more RCT studies that include selenium measurements in toenail samples and other biomaterials to evaluate short-term and transient changes in selenium intake.

Study Citation: Cui, Zhigang MD; Liu, Dezhong MD; Liu, Chun MD; Liu, Gang MD, Medicine (Baltimore). 2017 Feb;96(5):e5944. doi: 10.1097/MD.0000000000005944.

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Resources

1 Shamberger RJ, Frost DU. Possible protective effect of selenium against human cancer. Can Med Assoc J 1969;100:682–9.

2 Hardell L, Degerman A, Tomic R, et al. Levels of selenium in plasma and glutathione peroxidase in erythrocytes in patients with prostate cancer or benign hyperplasia. Eur J Cancer Prev 1995;4:91–5.

3 Nomura AM, Lee J, Stemmermann GN, et al. Serum selenium and subsequent risk of prostate cancer. Cancer Epidemiol Biomarkers Prev 2000;9:883–7.

4 Brooks JD, Metter EJ, Chan DW, et al. Plasma selenium level before diagnosis and the risk of prostate cancer development. J Urol 2001;166:2034–8.

5 Rejali L, Jaafar MH, Ismail NH. Serum selenium level and other risk factors for breast cancer among patients in a Malaysian hospital. Environ Health Prev Med 2007;12:105–10.

6 Carlos WG, Curtis Ramsey M, Fraiz J. Selenium in early sepsis: a marker for change? Advances in Sepsis 2007;6:99–102.

7  Van’T Veer P, Van der Wielen RP, Kok FJ. Selenium in diet, blood, and toenails in relation to breast cancer: a case-control study. Am J Epidemiol 1990;131:987–94.

8 Brigelius-Flohe R, Kelly FJ, Salonen JT, et al. The European perspective on vitamin E: current knowledge and future research. Am J Clin Nutr 2002;76:703–16.

9 Cooney RV, Franke AA, Harwood PJ, et al. Gamma-tocopherol detoxification of nitrogen dioxide: superiority to alphatocopherol. Proc Natl Acad Sci USA 1993;90:1771–5.

10 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;7:30139–51.

 

 

 

 

 

 

 

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