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Do antioxidants prevent colorectal cancer? A meta-analysis.
Rom J Intern Med 2013 Jul-Dec; 51(3-4):152-63RJ

Abstract

BACKGROUND

Oxidative stress is the first step involved in mutagenesis, carcinogenesis and aging. There has been great interest in recent years in potentially health benefits of dietary and antioxidant supplements in cancer prevention.

OBJECTIVES

Our primary objectives were to estimate the global effect of antioxidants on colorectal cancer incidence, adenomatous polyp recurrence, overall mortality and cancer related mortality. A secondary aim was to evaluate these effects across specific antioxidant compounds, dose and duration of antioxidant supplementation.

METHODS

Using Cochrane Collaboration methodology we searched for all randomized controlled trials (RCTs) from 1966 till May 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 obtained using random and fixed effect meta-analysis.

RESULTS

Twenty RCTs, including 26 8590 participants, were eligible: 12 analyzing the colorectal cancer incidence included 25 0676 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 random-effect 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 = 0.88, 95% CI, 0.55-1.40, p = 0.59), 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 combination with other antioxidants it 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.

CONCLUSIONS

This meta-analysis 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.

Authors

No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Meta-Analysis
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

24620628

Citation

Pais, Raluca, and D L. Dumitraşcu. "Do Antioxidants Prevent Colorectal Cancer? a Meta-analysis." Romanian Journal of Internal Medicine = Revue Roumaine De Medecine Interne, vol. 51, no. 3-4, 2013, pp. 152-63.
Pais R, Dumitraşcu DL. Do antioxidants prevent colorectal cancer? A meta-analysis. Rom J Intern Med. 2013;51(3-4):152-63.
Pais, R., & Dumitraşcu, D. L. (2013). Do antioxidants prevent colorectal cancer? A meta-analysis. Romanian Journal of Internal Medicine = Revue Roumaine De Medecine Interne, 51(3-4), pp. 152-63.
Pais R, Dumitraşcu DL. Do Antioxidants Prevent Colorectal Cancer? a Meta-analysis. Rom J Intern Med. 2013;51(3-4):152-63. PubMed PMID: 24620628.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Do antioxidants prevent colorectal cancer? A meta-analysis. AU - Pais,Raluca, AU - Dumitraşcu,D L, PY - 2014/3/14/entrez PY - 2014/3/14/pubmed PY - 2014/4/30/medline SP - 152 EP - 63 JF - Romanian journal of internal medicine = Revue roumaine de medecine interne JO - Rom J Intern Med VL - 51 IS - 3-4 N2 - BACKGROUND: Oxidative stress is the first step involved in mutagenesis, carcinogenesis and aging. There has been great interest in recent years in potentially health benefits of dietary and antioxidant supplements in cancer prevention. OBJECTIVES: Our primary objectives were to estimate the global effect of antioxidants on colorectal cancer incidence, adenomatous polyp recurrence, overall mortality and cancer related mortality. A secondary aim was to evaluate these effects across specific antioxidant compounds, dose and duration of antioxidant supplementation. METHODS: Using Cochrane Collaboration methodology we searched for all randomized controlled trials (RCTs) from 1966 till May 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 obtained using random and fixed effect meta-analysis. RESULTS: Twenty RCTs, including 26 8590 participants, were eligible: 12 analyzing the colorectal cancer incidence included 25 0676 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 random-effect 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 = 0.88, 95% CI, 0.55-1.40, p = 0.59), 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 combination with other antioxidants it 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. CONCLUSIONS: This meta-analysis 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. SN - 1220-4749 UR - https://www.unboundmedicine.com/medline/citation/24620628/Do_antioxidants_prevent_colorectal_cancer_A_meta_analysis_ L2 - http://www.diseaseinfosearch.org/result/1746 DB - PRIME DP - Unbound Medicine ER -