Green tea polyphenols (GTPs) are strong antioxidants and have been found to be antimutagenic and anticarcinogenic in many experimental models and several human epidemiologic studies. In a 3-mon intervention study, we found that GTPs at 500 mg and 1,000 mg significantly decreased blood and urinary aflatoxin (AF) biomarkers in high-risk residents for liver cancer. To further evaluate the efficacy of long-term intervention with GTPs on reduction of specific heaptocarcinogen biomarkers, we have measured AF biomarkers in 700 blood and urine samples collected from a 3-year intervention study with 500 mg GTPs in 1,800 residents in southern Guangxi, China. Serum AF-albumin (alb.) adducts was measured by radioimmunoassay and LC-MS method. Urinary AFM1 was measured by immunoaffinity column-HPLC-fluorescence method and adjusted by creatinine (creat.). Levels of serum AF-alb. adducts in the placebo group were constant, averaged 1.11±0.06 pmol/mg alb. (n=70; range: 0.1-3.11) for the baseline, 1.09±0.07 pmol/mg alb. (n=70; range: 0.17-3.3) for 1-mon, 1.04±0.06 pmol/mg alb. (n=70; range: 0.24-2.43) for 3-mon, 0.98±0.48 pmol/mg alb. (n= 70; range: 0.26-1.97) for 6-mon, and 0.97±0.05 pmol/mg alb. (n=70; range: 0.42-2.17) for 12-mon. While levels of serum AF-alb. adducts in 500-mg GTP treatment group were averaged 1.06±0.06 pmol/mg alb. (n=70; range: 0.10-2.77) for the baseline, 0.94±0.05 pmol/mg alb. (n=70; range: 0.10-2.09) for 1-mon, 0.91±0.04 pmol/mg alb. (n=70; range: 0.07-1.76) for 3-mon, 0.88±0.05 pmol/mg alb. (n=70; range: 0.06-1.85) for 6-mon, and 0.84±0.04 pmol/mg alb. (n=70; range: 0.07-2.23) for 12-mon. Trend analysis shows statistically significant decreases (p<0.05). Urinary levels of AFM1 in the placebo groups were averaged 17.38±2.24 ng/mg creat. (n=70; range: 0.9-40.8) for the baseline, 16.78±1.22 ng/mg creat. (n=70; range: 0.5-34.5) for 1-mon, 20.88±7.01 ng/mg creat. (n=70; range: 1.1-68.1) for 3-mon, 19.04±1.12 ng/mg creat. (n=70; range: 0.5-36.5) for 6-mon, and 21.02±8.22 ng/mg creat. (n=70; range: 0.9-70.2) for 12-mon. Urinary levels of AFM1 in 500-mg GTP treatment group were averaged 22.04±2.51 ng/mg creat. (n=70; range: 0.5-50.1) for baseline, 13.87±23.64 ng/mg creat. (n=70; range: 0.8-576.1) for 1-mon, 10.64±2.60 ng/mg creat. (n=70; range: 0.38-62.13) for 3-mon, 14.40 ± 1.85 ng/mg creat. (n=70; range: 4.68-36.72) for 6-mon, and 16.87±8.08 ng/mg creat.(n=70; range: 0.5-74.1) for 12-mon. Trend analysis also shows statistically significant decreases (p<0.05). Results from this study confirm that intervention with GTPs, not only significantly reduced the oxidative DNA damage biomarker, but also significantly modulate AF metabolism and metabolic activation, therefore, GTPs may have a protective effect against viral- and chemical-induced hepatocarcinogenesis in high-risk human populations. (Supported by the NCI research grant CA90997).

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 3905.

100th AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO