The results were published online in the Journal of the American Medical Association at 3 p.m. CDT today, and top researchers from the study will hold a press conference in San Antonio Wednesday afternoon.
“The impact of this study is profound,” said Ian M. Thompson Jr., M.D., director of the Cancer Therapy & Research Center at The University of Texas Health Science Center at San Antonio, and one of the study’s authors. “The concept that 50 percent of adults over the age of 60 are taking vitamin E, and that 23 percent are taking at least the dosage that was used for the study, suggests that many men are impacted by this study. Over 200,000 men per year are diagnosed with prostate cancer. The fact that vitamin E increases this risk by almost 20 percent means there is a potential for a substantial reduction in the number of men diagnosed with prostate cancer – simply by a change in supplements.”
Dr. Thompson will be joined at a Wednesday press conference by Laurence Baker, D.O., study co-author and chairman of SWOG, an international network of research institutions that carried out the Selenium and Vitamin E Cancer Prevention Trial (SELECT). Three patients from the study will also be available for interviews. The news conference is scheduled for 4 p.m. in the Mabee Conference Room on the 4th floor of the Grossman Building at the CTRC, 7979 Wurzbach Rd.
“We have evidence that vitamin A supplementation does not prevent lung cancer but rather increases the risk. Now, we have evidence that vitamin E doesn’t prevent prostate cancer but rather can increase the risk,” said Dr. Baker. “Understanding why this happens is important, especially with the increased use of vitamin D supplementation, as vitamins A, D and E are our common fat-soluble vitamins.”
SELECT is a randomized, double-blind, placebo-controlled study of 35,533 men assigned to four treatment groups. SELECT was funded by the National Cancer Institute (NCI) and other institutes that comprise the National Institutes of Health. SWOG carried out SELECT at more than 400 clinical sites in the United States, Puerto Rico, and Canada.
The men in SELECT either received selenium, vitamin E, both, or a placebo. SELECT was halted in 2008, its seventh year, after data showed no benefit from taking either supplement. Follow-up has revealed that in fact there is a statistically significant increase in prostate cancer risk.
SELECT researchers are now examining the levels of micronutrients in participants’ blood at the beginning of the trial, before they began taking SELECT supplements, to see how those levels may have affected risk for prostate cancer and how adding the supplements may have changed that risk. The participant samples come from the study biorepository of blood and toe nail clippings which is a resource for further study. Other researchers are looking at how genetic makeup could affect a man’s risk of developing prostate cancer while taking vitamin E.
“SWOG is soliciting proposals from researchers nationwide to use the SELECT biorepository to help answer the biological question of why vitamin E increased risk instead of decreasing it,” Dr. Baker said. “There are many more questions raised by these study results than we have answers for, and thus the need for further investigation.”
Dr. Thompson added, “We’ve often thought that the best source of vitamins is in the form of a pill. Unfortunately, when you do that you receive a limited number of the broad range of potentially beneficial substances found in Nature. Most likely, the best supplements are not manufactured and packaged by people, but are found in the produce section of your local grocery store.”
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Contact: Elizabeth Allen, CTRC, 210-450-2020