Randomized Trials of Antioxidant Supplementation for Cancer Prevention
First Bias, Now Chance—Next, Cause
- Peter H. Gann, MD, ScD
- Author Affiliation: Department of Pathology, University of Illinois at Chicago.
Since this article does not have an abstract, we have provided the first 150 words of the full text.
- KEYWORDS:
- ANTIOXIDANTS
- CLINICAL TRIALS, PHASE III AS TOPIC
- DATA INTERPRETATION, STATISTICAL
- DIET
- DIETARY SUPPLEMENTS
- MEN'S HEALTH
- NEOPLASMS
- PROSTATIC NEOPLASMS
- PROSTATE-SPECIFIC ANTIGEN
- RANDOMIZED CONTROLLED TRIALS AS TOPIC
- RESEARCH DESIGN
- SELENIUM
- VITAMIN E
Published online December 9, 2008 (doi:10.1001/jama.2008.863).
In 1996, a wave of hope arose when the Nutritional Prevention of Cancer trial reported a 65% reduction in prostate cancer incidence in men receiving selenium supplementation.1 This came only 2 years after the ATBC (α-Tocopherol, Beta Carotene) Cancer Prevention Trial had reported a 35% reduction in prostate cancer occurrence among men taking vitamin E supplements.2 Suddenly, it appeared to make sense that this cancer could be prevented by bolstering antioxidant defenses in middle-aged and older men. Prostate cancer was not a prespecified end point in either trial, and although both results were based on post hoc analysis, randomization had worked and it seemed unlikely that the encouraging findings were due to confounding bias. Indeed, confounding stood as the likely explanation for discordance between the earlier beta carotene trials that failed to demonstrate any benefit and numerous observational studies reporting that men …
