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Green Tea Shows Promise As Chemoprevention Agent For Oral Cancer
ScienceDaily (Nov. 5, 2009) — Green tea extract has shown promise as cancer prevention agent for oral cancer in patients with a pre-malignant condition known as oral leukoplakia, according to researchers at The University of Texas M. D. Anderson Cancer Center. The study, published online in Cancer Prevention Research, is the first to examine green tea as a chemopreventative agent in this high-risk patient population. The researchers found that more than half of the oral leukoplakia patients who took the extract had a clinical response. Long investigated in laboratory, epidemiological and clinical settings for several cancer types, green tea is rich in polyphenols, which have been known to inhibit carcinogenesis in preclinical models. Still, clinical results have been mixed. "While still very early, and not definitive proof that green tea is an effective preventive agent, these results certainly encourage more study for patients at highest risk for oral cancer," said Vassiliki Papadimitrakopoulou, M.D., professor in M. D. Anderson's Department of Thoracic/Head and Neck Medical Oncology, and the study's senior author. "The extract's lack of toxicity is attractive -- in prevention trials, it's very important to remember that these are otherwise healthy individuals and we need to ensure that agents studied produce no harm." In the Phase II dose-finding study, 41 M. D. Anderson oral leukoplakia patients were randomized between August 2002 and March 2008 to receive either green tea extract or placebo. Participants took the extract, an oral agent, for three months at one of three doses -- 500 per meter squared of body mass (mg/m2); 750 mg/m2 or 1,000 mg/m2 -- three times daily. To best assess biomarkers, participants also underwent a baseline and 12-week biopsy, an important component in the design of the study, the researchers say. "Collecting oral tissue biopsies was essential in that it allowed us to learn that not only did the green tea extract appear to have benefit for some patients, but we pointed to anti-angiogenic effects as a potential mechanism of action," said Anne Tsao, M.D., assistant professor in the Department of Thoracic/Head and Neck Medical Oncology, and the study's first author. "While preliminary because our patient population was so small, this gives us direction for further study." Of those taking green tea at the two highest doses, 58.8 percent had a clinical response, compared with 36.4 percent in the lowest extract dose and 18.2 percent in the placebo arm. At an extended follow-up with a mean of 27.5 months, 15 participants had developed oral cancer, with a median time to disease development of 46.4 months. Although not statistically significant, the green tea extract also improved histology and trended towards an improvement in a number of biomarkers that may play a vital role in predicting cancer development. Another important finding, say the researchers, was that that the extract was well tolerated. Side effects, including insomnia and nervousness, were mostly seen in the high-dose group but produced no significant toxicity. "While these are encouraging findings, much more research must be done before we can conclude that green tea may prevent oral or any other type of cancer. It's also important to remind people that this trial enrolled very few participants who, at the highest dose levels took the equivalent of eight cups of green tea three times a day," said Papadimitrakopoulo. "We need to further understand if green tea offers longer-term prevention effects for patients." Papadimitrakopoulo and Tsao think that future studies with green tea in this high-risk population should focus on participants being exposed to the supplement for a longer time period. The researchers also stressed that the green tea extract studied in this trial was never sold over-the-counter and/or the Internet, both of which are not highly regulated. Rather, the compound was exclusively developed as a pharmaceutical. According to the American Cancer Society, more than 35,720 are expected to be diagnosed with oral and/or pharynx cancer and the five year survival rate is less than 50 percent. The study was funded by Ito En, the company that produced the green tea extract. In addition to Papadimitrakopoulou and Tsao, other M. D. Anderson authors on the study include: Waun Ki Hong, M.D., professor and chair of the Division of Cancer Medicine; Jack Martin, D.D.S., professor in the Department of Dental Oncology; Li Mao, M.D., adjunct professor and Xi Ming Tang, M.D., Ph.D. research scientist, both of the Department of Thoracic/Head and Neck Medical Oncology; Adel El-Naggar, M.D., Ph.D., professor in the Department of Pathology; Iganacio Wistuba, M.D., professor in the Department of Pathology-Research; Kirk Culotta, Phar M.D., Department of Pharmacy Pharmacology Research; Ann Gillenwater, M.D., professor in the Department of Head and Neck Surgery; J. Jack Lee, Ph.D., professor and Diane Liu, both of the Department of Biostatistics. Other authors include Yuko Sagesaka of Ito En, Ltd.
Green Tea & Oral Cancer - Georgia Study
Green tea polyphenols are found to induce apoptosis (programmed cell death) in many types of tumor cells, including oral cancer cells. In a study done by the Department of Oral Biologyand Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, cell growth and invasion assays combined with apoptosis assays were used to examine the effects of green tea extracts, green tea polyphenols, and the most potent green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), on normal human keratinocytes and oral carcinoma cells. The results showed that green tea and its constituents selectively induce apoptosis only in oral carcinoma cells, while EGCG was able to inhibit the growth and invasion of oral carcinoma cells. These differential responses to green tea and its constituents between normal and malignant cells were correlated with the induction of p57, a cell cycle regulator. These data suggest that the chemopreventive effects of green tea polyphenols may involve a p57 mediated survival pathway in normal epithelial cells, while oral carcinoma cells undergo an apoptotic pathway. Therefore, regular consumption of green tea could be beneficial in the prevention of oral cancer.
Green Tea & Oral Cancer - Curcumin Study
One interesting recent study compared the effects of epigallocatechin gallate, curcumin (a powerful ant-carcinogenic compound from the curry spice turmeric), and the combination of both on an in-vitro model of oral cancer. It was found that epigallocatechin gallate helped arrest tumor cell growth in a different cell-cycle stage than curcumin. When the two compounds were combined, growth inhibition was enhanced, suggesting a synergistic effect.
References: Life Extension Magazine and other studies added.
Asano Y, Okamura S et al. Effect of epigallocatechin gallate on leukemic blastcells from patients with acute myeloblastic leukemia. Life Sci 1997; 60:135-42 Berger SJ, et al. Green tea constituent (--)-epigallocatechin-3-gallate inhibits topoisomerase I activity in human colon carcinoma cells. Biochem Biophys Res Commun 2001;288:101-5.
Challa A et al. Interactive suppression of aberrant crypt foci induced by azoxymethane in rat colon by phytic acid and green tea. Carcinogenesis 1997; 10:2023-26
Chen ZP, et al. Green tea epigallocatechin gallate shows a pronounced growth inhibitory effect on cancerous cells but not on their normal counterparts. Cancer Lett 1998; 129:173-79
Chung FL et al. Inhibition of lung carcinogenesis by black tea in Fischer rats treated with a tobacco-specific carcinogen: Caffeine as an important constituent. Cancer Res 1998;58:4096-4101
Deng ZY, Tao BY, et al. Effect of green tea and black tea on blood glucose, triglycerides, and antioxidants in aged rats. J Agricult Food Chem 1998;46:3875-78
Francheschi S et al. Influence of food groups and food diversity on breast cancer risk in Italy. Int J Cancer 1995; 63:785-89
Goodwin Sarah Federation of American Societies for Experimental Biology 18-Apr-2004
Hamilton-Miller JM. Anti-cariogenic properties of tea (Camellia sinensis). J Med Microbiol 2001;50:299-302
Hara Y. Influence of tea catechins on the digestive tract. J Cel Biochem 1997; Suppl 27: 52-58
Hibasami H et al. Induction of apoptosis in human stomach cancer cells by green tea catechins. Oncol Repetition 1998; 5:527-29
Hirose M et al. Inhibition of mammary gland carcinogenesis by green tea catechins and other naturally occurring antioxidants in female Sprague-Dawley rats pretreated with MDBA. Cancer Lett 1994; 83:149-56
Hong J, et al. Effects of purified green and black tea polyphenols on cyclooxygenase- and lipoxygenase-dependent metabolism of arachidonic acid in human colon mucosa and colon tumor tissues. Biochem Pharmacol 2001;62:1175-83
Hoshiyama Y, et al. A prospective study of stomach cancer death in relation to green tea consumption in Japan. Br J Cancer 2002;87:309-13
Huang MT, et al. Effects of tea, decaffeinated tea, and caffeine on UVB light-induced complete carcinogenesis in SKH-1 mice: demonstration of caffeine as a biologically important constituent of tea. Cancer Res 1997;57:2623-9
Hsu SD, et al. Chemoprevention of oral cancer by green tea. Gen Dent 2002;50:140-6
Inoue M, Tajima K, et al. Tea and coffee consumption and the risk of digestive tract cancers: data from a comparative case-referent study in Japan. Cancer Causes Control 1998;9:209-16
Ito Y et al. Chromosome aberrations induced by aflatoxin B1 in rat bone marrow cells in vivo and their suppression by green tea. Mutat Res 1989; 222:253-61
Jian L, Xie LP, Lee AH, Binns, CW Protective Effect Of Green Tea Against Prostate Cancer: A Case Control Study In Southeast China Int J Cancer:108. 130-135 (2004)
Katiyar SK, Mukhtar H. Tea antioxidants in cancer chemoprevention. J Cell Biochem Suppl 1997; 27:59-67
Katiyar SK et al. Polyphenolic antioxidant epigallocatechin gallate from green tea reduces UVB-induced inflammatory responses and infiltration of leukocytes in human skin. Photochem Photobiol 1999; 69:148-53
Khafif A; Schantz SP, et al. Quantitation of chemopreventive synergism between epigallocatechin gallate and curcumin in normal, premalignant, and malignant oral epithelial cells. Carcinogenesis 1998;19:419-24
Kinjo J, et al. Activity-guided fractionation of green tea extract with antiproliferative activity against human stomach cancer cells. Biol Pharm Bull 2002;25:1238-40
Komori A, Yasunami J, et al. Anticarcinogenic activity of green tea polyphenols. Jpn J Clin Oncol 1993; 23:186-90
Kuroda Y, Hara Y. Antimutagenic and anticarcinogenic activity of tea polyphenols. Mutat Res 1999; 436:69-97
Larsson, Susanna, Wolk Alicja, Karolinksa Institute. A relationship between the amounts of tea a middle-age woman drinks and her risk for ovarian cancer. Archives of Internal Medicine. Dec. 12 issue.
Lean ME et al. Dietary flavonols protect diabetic human lymphocytes against oxidative damage to DNA. Diabetes 1999; 48:176-81
Lee IP et al. Chemopreventive effects of green tea against cigarette smoke-induced mutations in humans. J Cell Biochem 1997; Suppl 27:68-75
Lee YK, et al. VEGF Receptor Phosphorylation Status and Apoptosis is Modulated by a Green Tea Component, Epigallocatechin-3-gallate (EGCG) in B cell Chronic Lymphocytic Leukemia. Blood 2004;104(3):788-94
Liao S, Hipakka RA. Selective inhibition of steroid 5-alpha-reductase isozymes by tea epicatechin-3-gallate and epigallocatechin-3-gallate. Biochem Biophys Res Commun 1995;214:833-38
Liao S, Umekita Y et al. Growth inhibition and regression of human prostate and breast tumors in athymic mice by tea epigallocatechin gallate. Cancer Lett 1995; 96:239-43
Lin YL, Cheng CY, et al. Hypolipidemic effect of green tea leaves through induction of antioxidant and phase II enzymes including superoxide dismutase, catalase, and glutathione S-transferase in rats. J Agricult Food Chem 1998;46:1893-99
Lu LH, Lee SS, Huang HC. Epigallocatechin suppression of proliferation of vascular smooth muscle cells: correlation with c-jun and JNK. Brit J Pharmacol 1998;124:1227-37
McCarty MF. Polyphenol-mediated inhibition of AP-1 transactivating activity may slow cancer growth by impeding angiogenesis and tumor invasiveness. Med Hypoth 1998; 50:511-14
Morre D, Morre DJ. Findings on epigallocatechin gallate and tNOX inhibition presented at the 38th annual meeting of the American Society for Cell Biology; summary available at http//www.uns.purdue.edu
Naasani I et al. Telomerase inhibition, telomere shortening, and senescence of cancer cells by tea catechins. Biochem Biophys Res Commun 1998; 249:391-96
Nagata C et al. Associations of coffee, green tea, and caffeine intakes with serum concentrations of estradiol and sex hormone-binding globulin in premenopausal Japanese women. Nutr Cancer 1998; 30:21-24
Nakachi K, Suemasu K, et al. Influence of drinking green tea on breast cancer malignancy among Japanese patients. Jpn J Cancer Res 1998;89:254-61
Oguri A et al. Inhibitory effects of antioxidants on formation of heterocyclic amines. Mutat Res 1998; 402:237-45
Otsuka T, Ogo T, et al. Growth inhibition of leukemic cells by epigallocatechin gallate, the main constituent of green tea. Life Sciences 1998; 63:1397-1403
Parshad R, Sanford RR, et al. Protective action of plant polyphenols on radiation-induced chromatid breaks in cultured human cells. Anticancer Res 1998;18:3263-66
Pashka AG et al. Induction of apoptosis in prostate cancer cell lines by the green tea component, epigallocatechin gallate. Cancer Lett 1998;130:1-7
Pisters KM, et al. Phase I trial of oral green tea extract in adult patients with solid tumors. J Clin Oncol 2001;19:1830-8.
Proniuk S, et al. Preformulation study of epigallocatechin gallate, a promising antioxidant for topical skin cancer prevention. J Pharm Sci 2002;91:111-6
Quin G et al. Inhibition of aflatoxin B1-induced initiation of hepatocarcinogenesis in the rat by green tea. Cancer Lett 1997; 112:149-54
Reuters. Green tea blocks angiogenesis. Internet Health News, 3-31-1999
Sai I, Kai S et al. Protective effects of green tea on hepatotoxicity, oxidative DNA damage and cell proliferation in the rat liver, induced by repeated oral administration of 2-nitropropane. Food Chem Toxicol 1998; 6:1043
Sartippour MR, et al. Green tea inhibits vascular endothelial growth factor (VEGF) induction in human breast cancer cells. J Nutr 2002;132:2307-11.
Sazuka M, Imazawa H, et al. Inhibition of collagenases from mouse lung carcinoma cells by green tea catechins and black tea theaflavins. Biosci Biotechnol Biochem 1997; 61:1504-06
Smith DM, et al. Green tea polyphenol epigallocatechin inhibits DNA replication and consequently induces leukemia cell apoptosis. Int J Mol Med 2001;7:645-52
Suganuma M, Okabe S, et al. Synergistic effects of epigallocatechin gallate with epicatechin, sunlilndac, or tamoxifen on cancer-preventive activity in the human lung cancer cell line PC-9. Cancer Res 1999;59:44-7
Sugiyama T, Sadzuka Y. Combination of theanine with doxorubicin inhibits hepatic metastasis of M5076 ovarian sarcoma. Clin Cancer Res 1999; 5:413-16
Sugiyama T, Sadzuka Y. Enhancing effects of green tea components on the antitumor activity of adriamycin against M5076 ovarian sarcoma. Cancer Lett 1998; 133:19-26
Sun CL, et al. Urinary tea polyphenols in relation to gastric and esophageal cancers: a prospective study of men in Shanghai, China. Carcinogenesis 2002;23:1497-503.
Tosetti F, Ferrari N, De Flora S. Angioprevention: angiogenesis is a common and key target for cancer chemopreventive agents. FASEB J 2002;16:2-14
Tsubono Y, et al. Green tea and the risk of gastric cancer in Japan. N Engl J Med 2001;344:632-6
Valcic S et al. Inhibitory effect of six green tea catechins and caffeine on the growth of four selected human tumor cell lines. Anticancer Drugs 1996; 7:461-68
Wang ZY, et al. Inhibitory effect of green tea on the growth of established skin papillomas in mice. Cancer Res 1992;52:6657-65.
Yamane T, Nakatsni H et al. Inhibitory effects and toxicity of green tea polyphenols for gastrointestinal carcinogenesis. Cancer 1996;77(suppl):1662-67
Yan YS. Effect of Chinese tea extract on the immune function of mice bearing tumors and their antitumor activity. Chung Hua Yu Fang 1992; 26:5-7
Yang CS, et al. Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers. Cancer Epidemiol Biomarkers Prev 1998;7:351-4.
Yang CS, et al. Prevention of carcinogenesis by tea polyphenols. Drug Metab Rev 2001;33:237-53
Yang CS, et al. Human salivary tea catechin levels and catechin esterase activities: implications in human cancer prevention studies. Cancer Epidemiol Biomarkers Prev 1999;8:83-9
Yang FJ et al. Green tea polyphenols block endotoxin-induced tumor necrosis factor alpha production and lethality in murine model. J Nutr 1998; 128:2334-40
Yang GY, Liao J, et al. Inhibition of growth and induction of apoptosis in human cancer cell lines by tea polyphenols. Carcinogenesis 1998; 19:611-16
Zhang, M, Binns, CW, Lee, A Tea Consumption and Ovarian Cancer Risk: A Case control Study in China. Cancer Epidemiol Biomarkers Prev (2002) 11:713-718.
Zhen Y et al. Green tea extract inhibits nucleoside transport and potentiates the antitumor effect of antimetabolites. Chin Med Sci 1991; 6:1-5
Zhu BT, Taneja N et al. Effects of tea polyphenols and flavonoids on liver microsomal glucuronidation of estradiol and estrone. J Steroid Biochem Mol Biol 1998;64:207-15