Selenium and Vitamin E Cancer Prevention Trial

The Selenium and Vitamin E Cancer Prevention Trial, or SELECT, was a clinical trial conducted with the goal of determining whether vitamin E and selenium supplements could prevent prostate cancer.[1] Enrollment for the trial began in 2001 and ended in 2004.[1] It cost approximately $114 million to conduct and was performed at over 400 different research centers.[2] It was primarily funded by the National Cancer Institute (NCI) and was carried out by SWOG.[1] It was stopped early because the supplements did not show any benefit in preventing prostate cancer. Subsequent research based on the trial has generally found that selenium and vitamin E do not prevent prostate cancer. Other research based on foods rich in selenium or Vitamin E, not supplements, suggests that there is limited evidence such foods may protect against some forms of cancer.[3]

Methodology

The study followed over 35,000 men in the United States, Puerto Rico, and Canada, who were assigned randomly to receive either both a selenium and vitamin E supplement, selenium and placebo, vitamin E and placebo, or two placebos.[4] It was one of the largest cancer prevention trials ever conducted,[5] and was described by the NCI as "the largest-ever prostate cancer prevention study."[6] Selenium and Vitamin E were chosen because they are well known antioxidants and had other mechanisms by which they were thought to prevent cancer, and preclinical and smaller clinical studies had yielded very promising results.[6][7]

The study was originally planned to last for twelve years after enrollment began.[8] However, it was stopped early in 2008 because no protective effect of supplementation on prostate cancer risk was found, and because the results suggested that vitamin E might increase the risk.[1] About 17,000 participants from the original SELECT completed an additional four years of a Centralized Follow-Up from 2010 until May 31, 2014, when SELECT closed.[9] The follow-up involved sending questionnaires to participants annually, which they could also fill out online.[1]

Results

Initial results were published in 2008 in JAMA.[10] The initial results found that the increase in risk associated with Vitamin E was "statistically nonsignificant",[10] which the researchers wanted to verify in a subsequent study.[11]

A subsequent 2010 study further described SELECT's results and found that neither selenium nor vitamin E, on their own or in combination, prevented prostate cancer.[12]

A 2011 study based on the trial found that the risk of prostate cancer was elevated by 17% in the group that took vitamin E supplements, which was statistically significant.[8][13]

A 2014 study based on SELECT data found that selenium supplementation increased the risk of high-grade prostate cancer in men who had a higher baseline selenium status.[14][15]

A 2014 Cochrane review found that SELECT raised concerns about a possible association between selenium supplements and an increase in risk of type 2 diabetes, alopecia and dermatitis. The review concluded that "no convincing evidence suggests that selenium supplements can prevent cancer in humans."[16]

References

  1. 1 2 3 4 5 Selenium and Vitamin E Cancer Prevention Trial Q&A
  2. ↑ Simon, Harvey B. (17 September 2009). "Do Vitamins Prevent Prostate Cancer?". Chicago Tribune. Retrieved 17 November 2014.
  3. ↑ World Cancer Research Fund , American Institute for Cancer Research.title=Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. (2007). Washington DC: AICR, (PDF) http://eprints.ucl.ac.uk/4841/1/4841.pdf. Missing or empty |title= (help)
  4. ↑ Neighmond, Patti (27 October 2008). "Study: Vitamin E Doesn't Prevent Prostate Cancer". NPR. Retrieved 17 November 2014.
  5. ↑ Hatfield, DL; Gladyshev, VN (February 2009). "The Outcome of Selenium and Vitamin E Cancer Prevention Trial (SELECT) reveals the need for better understanding of selenium biology.". Molecular interventions. 9 (1): 18–21. doi:10.1124/mi.9.1.6. PMID 19299660.
  6. 1 2 Largest-Ever Prostate Cancer Prevention Trial Opens: 32,000 Men Sought to Test Vitamin E and Selenium
  7. ↑ Klein EA SELECT: the selenium and vitamin E cancer prevention trial.Urol Oncol. 2003 Jan-Feb;21(1):59-65. PMID 12684129
  8. 1 2 "Selenium, vitamin E supplements may up prostate cancer risk". UPI. 21 February 2014. Retrieved 17 November 2014.
  9. ↑ SELECT
  10. 1 2 Lippman, Scott M.; Klein, Eric A.; Goodman, Phyllis J.; Lucia, M. Scott; Thompson, Ian M.; Ford, Leslie G.; Parnes, Howard L.; Minasian, Lori M.; Gaziano, J. Michael; Hartline, Jo Ann; Parsons, J. Kellogg; Bearden, James D.; Crawford, E. David; Goodman, Gary E.; Claudio, Jaime; Winquist, Eric; Cook, Elise D.; Karp, Daniel D.; Walther, Philip; Lieber, Michael M.; Kristal, Alan R.; Darke, Amy K.; Arnold, Kathryn B.; Ganz, Patricia A.; Santella, Regina M.; Albanes, Demetrius; Taylor, Philip R.; Probstfield, Jeffrey L.; Jagpal, T. J.; Crowley, John J.; Meyskens, Frank L.; Baker, Laurence H.; Coltman, Charles A. (7 January 2009). "Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers". JAMA. 301 (1): 39–51. doi:10.1001/jama.2008.864. PMID 19066370.
  11. ↑ Jaslow, Ryan (5 August 2013). "Too much vitamin E tied to prostate cancer risk". CBS News. Retrieved 17 November 2014.
  12. ↑ Dunn, BK; Richmond, ES; Minasian, LM; Ryan, AM; Ford, LG (2010). "A nutrient approach to prostate cancer prevention: The Selenium and Vitamin E Cancer Prevention Trial (SELECT).". Nutrition and cancer. 62 (7): 896–918. doi:10.1080/01635581.2010.509833. PMID 20924966.
  13. ↑ Klein, Eric A.; Thompson, Ian M.; Tangen, Catherine M.; Crowley, John J.; Lucia, M. Scott; Goodman, Phyllis J.; Minasian, Lori M.; Ford, Leslie G.; Parnes, Howard L.; Gaziano, J. Michael; Karp, Daniel D.; Lieber, Michael M.; Walther, Philip J.; Klotz, Laurence; Parsons, J. Kellogg; Chin, Joseph L.; Darke, Amy K.; Lippman, Scott M.; Goodman, Gary E.; Meyskens, Frank L.; Baker, Laurence H. (12 October 2011). "Vitamin E and the Risk of Prostate Cancer". JAMA. 306 (14): 1549–56. doi:10.1001/jama.2011.1437. PMID 21990298.
  14. ↑ Kristal, A. R.; Darke, A. K.; Morris, J. S.; Tangen, C. M.; Goodman, P. J.; Thompson, I. M.; Meyskens, F. L.; Goodman, G. E.; Minasian, L. M.; Parnes, H. L.; Lippman, S. M.; Klein, E. A. (22 February 2014). "Baseline Selenium Status and Effects of Selenium and Vitamin E Supplementation on Prostate Cancer Risk". JNCI Journal of the National Cancer Institute. 106 (3): djt456–djt456. doi:10.1093/jnci/djt456.
  15. ↑ Press Association (21 February 2014). "Some vitamin supplements raise risk of cancer in men, research shows". The Guardian. Retrieved 17 November 2014.
  16. ↑ Vinceti, M; Dennert, G; Crespi, CM; Zwahlen, M; Brinkman, M; Zeegers, MP; Horneber, M; D'Amico, R; Del Giovane, C (30 March 2014). "Selenium for preventing cancer". The Cochrane database of systematic reviews. 3: CD005195. doi:10.1002/14651858.CD005195.pub3. PMID 24683040.
This article is issued from Wikipedia - version of the 10/17/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.