Article

Meta-analysis: Antioxidant supplements for primary and secondary prevention of colorectal adenoma

The Cochrane Hepato-Biliary Group, Copenhagen Trial Unit, Centre for Clinical Intervention Research, Copenhagen University Hospital, H:S Rigshospitalet, Copenhagen, Denmark.
Alimentary Pharmacology & Therapeutics (Impact Factor: 5.48). 07/2006; 24(2):281-91. DOI: 10.1111/j.1365-2036.2006.02970.x
Source: PubMed

ABSTRACT Colorectal cancer may be prevented by reducing the development of adenomatous polyps.
To assess the benefits and harms of antioxidant supplements in preventing colorectal adenoma.
Using the Cochrane Collaboration methodology we reviewed all randomized clinical trials comparing antioxidant supplements with placebo or no intervention. We searched electronic databases and the reference lists until October 2005. Outcome measures were development of colorectal adenoma adverse events. We analysed dichotomous outcomes with fixed- and random-effects model meta-analyses and calculated the relative risk with 95% confidence interval.
We identified eight randomized trials (17 620 participants). Neither fixed-effect (relative risk: 0.93, 95% CI: 0.81-1.1) nor random-effect model meta-analyses (0.82, 0.60-1.1) showed statistically significant effects of supplementation with beta-carotene, vitamins A, C, E and selenium alone or in combination. Antioxidant supplements seemed to increase the development of colorectal adenoma in three low-bias risk trials (1.2, 0.99-1.4) and significantly decrease its development in five high-bias risk trials (0.59, 0.47-0.74). The estimates difference is significant (P < 0.0001). There was no significant difference between the intervention groups regarding adverse events, including mortality (0.82, 0.47-1.4).
We found no convincing evidence that antioxidant supplements have significant beneficial effect on primary or secondary prevention of colorectal adenoma.

Download full-text

Full-text

Available from: Christian Gluud, Sep 15, 2014
0 Followers
 · 
103 Views
  • Source
    • "The results of another meta-analysis indicate that antioxidants do not seem to have a beneficial effect on preventing the recurrence of colorectal adenomas.55 "
    [Show abstract] [Hide abstract]
    ABSTRACT: Cancer is a worldwide problem as it will affect one in three men and one in four women during their lifetime. Colorectal cancer (CRC) is the third most frequent cancer in men, after lung and prostate cancer, and is the second most frequent cancer in women after breast cancer. It is also the third cause of death in men and women separately, and is the second most frequent cause of death by cancer if both genders are considered together. CRC represents approximately 10% of deaths by cancer. Modifiable risk factors of CRC include smoking, physical inactivity, being overweight and obesity, eating processed meat, and drinking alcohol excessively. CRC screening programs are possible only in economically developed countries. However, attention should be paid in the future to geographical areas with ageing populations and a western lifestyle.19,20 Sigmoidoscopy screening done with people aged 55-64 years has been demonstrated to reduce the incidence of CRC by 33% and mortality by CRC by 43%.
    Clinical Medicine Insights: Gastroenterology 07/2014; 7:33-46. DOI:10.4137/CGast.S14039
  • Source
    • "[21], [22] Dietary supplement use and colorectal adenoma risk have been extensively investigated in the general population. No convincing evidence for an association between multivitamin supplement use, [23] folic acid supplement use, [24] and antioxidant supplement use and adenoma occurrence was found, [25], [26] whereas calcium supplement use might contribute to a lower risk of colorectal adenomas. [27] MMR gene mutation carriers might have a higher use of dietary supplements compared to the general Dutch population based on their health status and risk. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Individuals with Lynch syndrome have a high lifetime risk of developing colorectal tumors. In this prospective cohort study of individuals with Lynch syndrome, we examined associations between use of dietary supplements and occurrence of colorectal adenomas. Using data of 470 individuals with Lynch syndrome in a prospective cohort study, associations between dietary supplement use and colorectal adenoma risk were evaluated by calculating hazard ratios (HR) and 95% confidence intervals (CI) using cox regression models adjusted for age, sex, and number of colonoscopies during person time. Robust sandwich covariance estimation was used to account for dependency within families. Of the 470 mismatch repair gene mutation carriers, 122 (26.0%) developed a colorectal adenoma during an overall median person time of 39.1 months. 40% of the study population used a dietary supplement. Use of any dietary supplement was not statistically significantly associated with colorectal adenoma risk (HR = 1.18; 95%CI 0.80-1.73). Multivitamin supplement use (HR = 1.15; 95%CI 0.72-1.84), vitamin C supplement use (HR = 1.57; 95%CI 0.93-2.63), calcium supplement use (HR = 0.69; 95%CI 0.25-1.92), and supplements containing fish oil (HR = 1.60; 95%CI 0.79-3.23) were also not associated with occurrence of colorectal adenomas. This prospective cohort study does not show inverse associations between dietary supplement use and occurrence of colorectal adenomas among individuals with Lynch syndrome. Further research is warranted to determine whether or not dietary supplement use is associated to colorectal adenoma and colorectal cancer risk in MMR gene mutation carriers.
    PLoS ONE 06/2013; 8(6):e66819. DOI:10.1371/journal.pone.0066819 · 3.23 Impact Factor
  • Source
    • "A high-quality meta-analysis of eight trials found that, compared with no treatment or placebo, there was no benefit of antioxidants (beta-carotene, vitamin A, vitamin C, vitamin E, or selenium) in decreasing the risk of CRC. Vitamin E was, in fact, found to increase the risk of colorectal adenomas [28]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Colorectal cancer (CRC) is common and is associated with a considerable mortality. Morbidity and thereby mortality can be reduced by using different prevention strategies such as lifestyle interventions and chemoprevention. Endoscopic surveillance of high-risk individuals and population-based endoscopic screening of average-risk individuals enables detection and removal of premalignant lesions (adenomas) as well as presymptomatic detection of cancer. Implementation of cancer detection tests such as fecal occult blood tests (FOBTs) is another strategy to reduce cancer mortality by early detection of CRC. Personalized management, based on estimates of the individual risk using information concerning environmental factors, lifestyle, family history, personality, social background and phenotype in combination with a variety of biomarkers such as genotype, will become more important as a strategy to optimize CRC prevention in the future.
    09/2010; 1(3):513-21. DOI:10.1007/s13167-010-0047-9
Show more