Wednesday, February 18, 2009

Chemoprevention Fails Again - Selenium and Vitamin E Fail to Prevent Prostate Cancer

JAMA. 2009;301(1):39-51

Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT)

Context Secondary analyses of 2 randomized controlled trials and supportive epidemiologicand preclinical data indicated the potential of selenium and vitamin E forpreventing prostate cancer.

Objective To determine whether selenium, vitamin E, or both could prevent prostatecancer and other diseases with little or no toxicity in relatively healthy men.

Design, Setting, and Participants A randomized, placebo-controlled trial (Seleniumand Vitamin E Cancer Prevention Trial [SELECT]) of 35 533 men from 427 participating sites in the United States, Canada, and Puerto Rico randomly assigned to 4 groups (selenium, vitamin E, selenium vitamin E, and placebo) in a double-blindfashion between August 22, 2001, and June 24, 2004. Baseline eligibility included age 50 years or older (African American men) or 55 years or older (all other men), a serumprostate-specific antigen level of 4 ng/mL or less, and a digital rectal examination notsuspicious for prostate cancer.

Interventions Oral selenium (200 $B&L(Bg/d from L-selenomethionine) and matched vitaminE placebo, vitamin E (400 IU/d of all rac- -tocopheryl acetate) and matchedselenium placebo, selenium vitamin E, or placebo placebo for a planned follow-up of minimum of 7 years and a maximum of 12 years.Main Outcome Measures Prostate cancer and prespecified secondary outcomes,including lung, colorectal, and overall primary cancer.

Results As of October 23, 2008, median overall follow-up was 5.46 years (range,4.17-7.33 years). Hazard ratios (99% confidence intervals [CIs]) for prostate cancerwere 1.13 (99% CI, 0.95-1.35; n=473) for vitamin E, 1.04 (99% CI, 0.87-1.24; n=432)for selenium, and 1.05 (99% CI, 0.88-1.25; n=437) for selenium vitamin E vs 1.00(n=416) for placebo. There were no significant differences (all P .15) in any otherprespecified cancer end points. There were statistically nonsignificant increased risks of prostate cancer in the vitamin E group (P=.06) and type 2 diabetes mellitus in the selenium group (relative risk, 1.07; 99% CI, 0.94-1.22; P=.16) but not in the selenium vitamin E group.

Conclusion Selenium or vitamin E, alone or in combination at the doses and formulations used, did not prevent prostate cancer in this population of relatively healthy men.
BrooklynDodger(s) Comments: Seems like the bloom will never be off the funding rose for chemoprevention. Imagine what a 35000 person study cost!!! And, starting in 2001 against a backdrop of mostly failed clinical trials of anti oxidant chemoprevention. The trail did not run long enough to evaluate the hazard of these treatments, although it suggests Selenium may increase risks of prostate cancer and type II diabetes. Schadenfreud aside, the anti-oxidant model posits that initiation by oxidant mechanisms is reduced by the treatment. By 55, most men are initiated. So the trial doesn't really test the model. Vitamins are likely good for cancer cells as well as regular cells, so increased cancer is a likely outcome of late stage treatment. The Dodger(s) confess not to know the street doses which gullibles take to prevent cancer, to compare with those in this study.

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