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Meta-Analysis
. 2012 Nov 21:12:165.
doi: 10.1186/1471-230X-12-165.

Green tea consumption and risk of esophageal cancer: a meta-analysis of epidemiologic studies

Ping Zheng  1 , Hai-Ming Zheng, Xing-Ming Deng, Yang-de Zhang
Affiliations
Meta-Analysis

Green tea consumption and risk of esophageal cancer: a meta-analysis of epidemiologic studies

Ping Zheng et al. BMC Gastroenterol. .

Abstract

Background: Green tea has shown the role of chemoprevention for cancer. Recently, several studies suggested that green tea intake may have effect on esophageal cancer risk, whereas the results were inconsistent.

Methods: We performed a meta-analysis of all English and Chinese language studies of green tea consumption and esophageal cancer risk indexed in Medline, Embase, the Science Citation Index, the Chinese Biomedical Database and Wanfang Data from 1980 to June 2012. After reviewing each study, extracting data, and evaluating heterogeneity (Chi-square-based Q test and Ι2) and publication bias (Begg and Egger test), a meta-analysis was performed to evaluate the association between high/medium/low green tea consumption and non-drinking esophageal cancer risk. Pooled relative risk (RR) or odds ratio (OR) with 95% confidence intervals (CIs) were calculated using the fixed- or random-effect models.

Results: Ten eligible epidemiologic studies including 33731 participants and 3557 cases for esophageal cancer were included. Eight of which were case-control studies, and two were cohort studies. Overall, there were no association between high/medium/low green tea consumption and non-drinking risk of esophageal cancer (High: highest vs non-drinker: RR/OR = 0.76, 95% CI: 0.49 to 1.02. Medium: drinker vs non-drinker: RR/OR = 0.86, 95% CI: 0.70 to 1.03. Low: lowest vs non-drinker: RR/OR = 0.83, 95% CI: 0.58 to 1.08). When stratified analyses according to study design (case-control and cohort studies), country (China and Japan), participates source (population-based and hospital-based case-control), and gender (female and male), there were significant association between high/medium/low green tea consumption and non-drinking risk of esophageal cancer among female (High: RR/OR = 0.32, 95% CI: 0.10 to 0.54. Medium: RR/OR = 0.43, 95% CI: 0.21 to 0.66. Low: RR/OR = 0.45, 95% CI: 0.10 to 0.79), but not the others.

Conclusions: We did not found significant association between green tea consumption and non-drinking esophageal cancer risk, but an evidence of protective effect was observed among female.

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Figures

Figure 1
Figure 1
Begg’s funnel plot of studies on high green tea intake and esophageal cancer risk about results of the included studies. The solid line in the center is the natural logarithm of pooled relative risk ratio (RR/OR), and two oblique lines are pseudo 95% confidence limits. SE, standard error.
Figure 2
Figure 2
Forest plot: Results of the studies on high green tea intake. The size of the data markers (squares) corresponds to the weight of the study in the meta-analysis. The combined relative risk is calculated using the random effects method.
Figure 3
Figure 3
Begg’s funnel plot of studies on medium green tea intake and esophageal cancer risk about results of the included studies. The solid line in the center is the natural logarithm of pooled relative risk ratio (RR/OR), and two oblique lines are pseudo 95% confidence limits. SE, standard error.
Figure 4
Figure 4
Forest plot: Results of the studies on medium green tea intake. The size of the data markers (squares) corresponds to the weight of the study in the meta-analysis. The combined relative risk is calculated using the random effects method.
Figure 5
Figure 5
Begg’s funnel plot of studies on low green tea intake and esophageal cancer risk about results of the included studies. The solid line in the center is the natural logarithm of pooled relative risk ratio (RR/OR), and two oblique lines are pseudo 95% confidence limits. SE, standard error.
Figure 6
Figure 6
Forest plot: Results of the studies on low green tea intake. The size of the data markers (squares) corresponds to the weight of the study in the meta-analysis. The combined relative risk is calculated using the random effects method.
See this image and copyright information in PMC

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