There have been no studies on specific
tea polyphenol biomarkers and risk of
colorectal cancer in humans. We prospectively examined the associations between validated
biomarkers of specific
tea polyphenols and risk of developing
colorectal cancer among a cohort of 18,244 men in Shanghai, China, with 16 years of follow-up.
Epigallocatechin (EGC),
4'-O-methyl-epigallocatechin (4'-MeEGC) and
epicatechin, and their metabolites in baseline urine samples were measured on 162 incident
colorectal cancer cases and 806 matched controls. Individuals with high prediagnostic urinary EGC levels had a lower risk of
colon cancer. Compared with undetectable EGC, odds ratios (95% confidence interval) for
colon cancer in the lowest, intermediate and highest tertile of detectable EGC were 0.64 (0.33-1.24), 0.60 (0.30-1.20) and 0.40 (0.19-0.83), respectively (p for trend = 0.02). A similar inverse relation between
4'-MeEGC and
colon cancer also was observed. Compared with the lowest quartile, odds ratios (95% confidence intervals) for
colon cancer in the 2nd, 3rd and 4th quartiles of urinary
4'-MeEGC were 0.49 (0.25-0.96), 0.32 (0.16-0.67) and 0.41 (0.20-0.84), respectively (p for trend = 0.006). The strongest protective effect was seen for regular
tea drinkers who showed high levels of urinary EGC and
4'-MeEGC. No association between urinary levels of
epicatechin or its metabolite and
colon cancer risk was observed. Urinary levels of
tea polyphenols and their metabolites were not associated with
rectal cancer risk. The present study supports the notion of
tea catechins as chemopreventive agents against the development of
colon cancer in humans.