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Meta-Analysis
. 2013 Apr;24(4):1079-87.
doi: 10.1093/annonc/mds601. Epub 2012 Dec 4.

Cruciferous Vegetables Intake and the Risk of Colorectal Cancer: A Meta-Analysis of Observational Studies

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Free PMC article
Meta-Analysis

Cruciferous Vegetables Intake and the Risk of Colorectal Cancer: A Meta-Analysis of Observational Studies

Q J Wu et al. Ann Oncol. .
Free PMC article

Abstract

Background: Epidemiological studies have reported inconsistent associations between cruciferous vegetable (CV) intake and colorectal cancer (CRC) risk. To our knowledge, a comprehensive and quantitative assessment of the association between CV intake and CRC has not been reported.

Methods: Relevant articles were identified by searching MEDLINE. We pooled the relative risks (RR) from individual studies using a random-effect model and carried out heterogeneity and publication bias analyses.

Results: Twenty-four case-control and 11 prospective studies were included in our analysis. When all studies were pooled, we yielded a significantly inverse association between CV (RR: 0.82; 95% confidence interval 0.75-0.90) intake and CRC risk. Specific analysis for cabbage and broccoli yielded similar result. When separately analyzed, case-control studies of CV intake yield similar results, and the results from the prospective studies showed borderline statistical significance. Moreover, significant inverse associations were also observed in colon cancer and its distal subsite both among prospective and case-control studies.

Conclusions: Findings from this meta-analysis provide evidence that high intake of CV was inversely associated with the risk of CRC and colon cancer in humans. Further analysis on other specific CV, food preparation methods, stratified results by anatomic cancer site, and subsite of colon cancer should be extended in future study.

Figures

Figure 1.
Figure 1.
Selection of studies for inclusion in meta-analysis
Figure 2.
Figure 2.
Forest plot (random-effect model) of cabbage consumption and colorectal cancer risk. Squares indicate study-specific relative risks (size of the square reflects the study-specific statistical weight); horizontal lines indicate 95% CIs; the diamond indicates the summary relative risk estimate with its 95% CI. CI, confidence interval; F, females; M, males; RR, relative risk.
Figure 3.
Figure 3.
Forest plot (random-effect model) of broccoli consumption and colorectal cancer risk. Squares indicate study-specific relative risks (size of the square reflects the study-specific statistical weight); horizontal lines indicate 95% CIs; the diamond indicates the summary relative risk estimate with its 95% CI. CI, confidence interval; F, females; RR, relative risk.
Figure 4.
Figure 4.
Forest plot (fixed-effect model) of cruciferous vegetables consumption and colorectal cancer risk in prospective studies. Squares indicate study-specific relative risks (size of the square reflects the study-specific statistical weight); horizontal lines indicate 95% CIs; the diamond indicates the summary relative risk estimate with its 95% CI. CI, confidence interval; F, females; M, males; RR, relative risk.
Figure 5.
Figure 5.
Forest plot (random-effect model) of cruciferous vegetables consumption and colorectal cancer risk in case–control studies. Squares indicate study-specific relative risks (size of the square reflects the study-specific statistical weight); horizontal lines indicate 95% CIs; the diamond indicates the summary relative risk estimate with its 95% CI. CI, confidence interval; M, males; RR, relative risk.

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