Selenium and Vitamin E Cancer Prevention Trial explained

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] __TOC__

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. 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.[8] 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.[9] The initial results found that the increase in risk associated with Vitamin E was "statistically nonsignificant",[9] which the researchers wanted to verify in a subsequent study.[10]

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.[11]

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.[12] [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]

Notes and References

  1. http://www.cancer.gov/newscenter/qa/2008/selectqa Selenium and Vitamin E Cancer Prevention Trial Q&A
  2. Web site: Do Vitamins Prevent Prostate Cancer? . Chicago Tribune . 17 September 2009 . 17 November 2014 . Simon, Harvey B..
  3. Web site: Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective.. World Cancer Research Fund, American Institute for Cancer Research . Washington DC: AICR. 2007. dead. https://web.archive.org/web/20130310124139/http://eprints.ucl.ac.uk/4841/1/4841.pdf. 2013-03-10.
  4. Web site: Study: Vitamin E Doesn't Prevent Prostate Cancer . NPR . 27 October 2008 . 17 November 2014 . Neighmond, Patti.
  5. Hatfield DL, Gladyshev VN . 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 . February 2009 . 19299660 . 2718722 . 10.1124/mi.9.1.6 .
  6. https://web.archive.org/web/20121028200856/http://www.cancer.gov/newscenter/newsfromnci/2001/select Largest-Ever Prostate Cancer Prevention Trial Opens: 32,000 Men Sought to Test Vitamin E and Selenium
  7. Klein EA, Thompson IM, Lippman SM, Goodman PJ, Albanes D, Taylor PR, Coltman C . SELECT: the selenium and vitamin E cancer prevention trial . Urologic Oncology . 21 . 1 . 59–65 . 2003 . 12684129 . 10.1016/S1078-1439(02)00301-0 .
  8. http://swog.org/Visitors/select/ SELECT
  9. Lippman SM, Klein EA, Goodman PJ, Lucia MS, Thompson IM, Ford LG, Parnes HL, Minasian LM, Gaziano JM, Hartline JA, Parsons JK, Bearden JD, Crawford ED, Goodman GE, Claudio J, Winquist E, Cook ED, Karp DD, Walther P, Lieber MM, Kristal AR, Darke AK, Arnold KB, Ganz PA, Santella RM, Albanes D, Taylor PR, Probstfield JL, Jagpal TJ, Crowley JJ, Meyskens FL, Baker LH, Coltman CA . 6 . Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT) . JAMA . 301 . 1 . 39–51 . January 2009 . 19066370 . 3682779 . 10.1001/jama.2008.864 .
  10. Web site: Too much vitamin E tied to prostate cancer risk . CBS News . 5 August 2013 . 17 November 2014 . Jaslow, Ryan.
  11. Dunn BK, Richmond ES, Minasian LM, Ryan AM, Ford LG . A nutrient approach to prostate cancer prevention: The Selenium and Vitamin E Cancer Prevention Trial (SELECT) . Nutrition and Cancer . 62 . 7 . 896–918 . 2010 . 20924966 . 10.1080/01635581.2010.509833 . 20297799 .
  12. Web site: Selenium, vitamin E supplements may up prostate cancer risk . UPI . 21 February 2014 . 17 November 2014.
  13. Klein EA, Thompson IM, Tangen CM, Crowley JJ, Lucia MS, Goodman PJ, Minasian LM, Ford LG, Parnes HL, Gaziano JM, Karp DD, Lieber MM, Walther PJ, Klotz L, Parsons JK, Chin JL, Darke AK, Lippman SM, Goodman GE, Meyskens FL, Baker LH . 6 . Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT) . JAMA . 306 . 14 . 1549–56 . October 2011 . 21990298 . 4169010 . 10.1001/jama.2011.1437 .
  14. Kristal AR, Darke AK, Morris JS, Tangen CM, Goodman PJ, Thompson IM, Meyskens FL, Goodman GE, Minasian LM, Parnes HL, Lippman SM, Klein EA . 6 . Baseline selenium status and effects of selenium and vitamin e supplementation on prostate cancer risk . Journal of the National Cancer Institute . 106 . 3 . djt456 . March 2014 . 24563519 . 3975165 . 10.1093/jnci/djt456 .
  15. Web site: Some vitamin supplements raise risk of cancer in men, research shows . The Guardian . 21 February 2014 . 17 November 2014 . Press Association.
  16. Vinceti M, Filippini T, Del Giovane C, Dennert G, Zwahlen M, Brinkman M, Zeegers MP, Horneber M, D'Amico R, Crespi CM . 6 . Selenium for preventing cancer . The Cochrane Database of Systematic Reviews . 1 . CD005195 . January 2018 . 2 . 29376219 . 6491296 . 10.1002/14651858.CD005195.pub4 .

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