Urinary biomarkers of tea polyphenols and risk of colorectal cancer in the Shanghai Cohort Study.

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.