M1195 Phase II Chemoprevention Trial of Atorvastatin (ATOR), Sulindac (Sul), Oligofructose-Enriched Inulin (Ofei), or Ofei Placebo (Ofeip) Among Subjects at Increased Risk for Sporadic Colorectal Cancer (CRC): A Cancer Prevention Network (CPN) Trial

Abstract

G A A b st ra ct s mortality and cancer related mortality. A secondary aim was to evaluate these effects across specific antioxidant compound, dose and duration of antioxidants supplementation. Using Cochrane Collaborationmethodology we searched for all randomized controlled trials (RCTs) from 1966 toMay 2009 (MEDLINE, Cochrane Controlled Clinical Trials Registry), comparing antioxidant supplements with placebo or no intervention on the occurrence of colorectal cancer or adenoma. The results expressed as relative risk (RR) and 95% confidence intervals (95% CI) were obtain using random and fixed effect meta-analysis. Twenty RCTs, including 268590 participants were eligible: 12 analyzing the colorectal cancer incidence included 250676 participants and 8 analyzing colorectal adenoma recurrence included 17914 participants. Antioxidant supplements had no significant effect on colorectal cancer incidence or colorectal adenoma recurrence (RR = 0, 94, 95% CI 0,84 1,06, p = 0,32) in a randomeffect meta-analysis. The antioxidant supplements had no significant effect on overall mortality (RR = 1,03, 95% CI 0,99 1,07, p = 0,12) or cancer related mortality (RR = 1,05, 95% CI 0,94 1,16, p = 0,38) in a random effect meta-analysis. Selenium supplementation was associated with a trend in reducing colorectal cancer incidence, (RR = 0,77, 95% CI 0,36 1,62, p = 0,49), colorectal adenoma recurrence (RR = 0,70, 95% CI 0,43 1,14, p = 0,16) and overall mortality (RR = 0,91, 95% CI 0,82-1,02, p = 0,09). Beta carotene alone was associated with a slight increase in colorectal cancer incidence (RR = 1,09, 95% CI = 0,92 1,29, p = 0,34) and in combinations with other antioxidants was associated with an increase in mortality (RR = 1,05, 95% CI = 0,99 1,11, p = 0,10). For both selenium and beta carotene, the effect was not statistically significant. Vitamin C and Vitamin E combination slightly reduced colorectal cancer incidence with no effect on overall mortality. This metaanalysis found no evidence in favor of a protective effect of the studied antioxidant supplements in the prevention of colorectal cancer or cancer related mortality. Only selenium supplementation might have anticarcinogenic effects and requires further research.