Green Tea & Cancer - Read what noted Oncologist Dr. Mitchell Gaynor's has to say about green tea. Select from our updated articles database for specific cancers:
Green Tea Could Help Prevent Cancer in Smokers
Researchers at Arizona Cancer Center, University of Arizona, suggest that a green tea concentrate may help some people boost their metabolic defense against toxins capable of causing cancer. In a study of 42 people, the concentrate, composed of chemicals known as green tea catechins in amounts equal to that found in 8-16 cups of green tea, boosted production of the enzymes, which belong to the glutathione S-transferase (GST) family, by as much as 80 percent in some participants. GST enzymes are believed to be crucial to the body's defense against cancer-causing chemicals and other toxins, according to the study's lead investigator, H.-H. Sherry Chow, Ph.D., a research associate professor at the University of Arizona. "They actually convert known carcinogens to non-toxic chemicals, and studies have shown a correlation between deficient expression of these enzymes and increased risk of developing some cancers," Chow said. "Expression of this enzyme varies dramatically in people due to genetic variation and environmental factors," Chow added. "Green tea catechins somehow increase gene expression of these enzymes, which can be an advantage to people with low levels to start with," he added. The study was intended to see if green tea catechin concentrate had any effect on the levels of GST enzymes in healthy individuals, an examination that could explain the tea's anti-cancer properties. Healthy volunteers were asked to abstain from consuming any tea or tea-related products for four weeks and then blood was drawn and baseline GST enzyme levels were determined. After taking the green tea concentrate for four weeks, a second blood test was taken. Researchers found that little variation occurred for those with high or medium GST levels. But it had its most significant effect in volunteers whose baseline blood measurements showed low GST activity, an 80 percent increase compared to baseline GST activity. "This is the first clinical study to show proof that chemicals in green tea can increase detoxification enzymes in humans. There may be other mechanism in play by which green tea may protect against cancer development, but this is a good place to start," Chow said. The study is published in the August issue of Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
Lung Cancer: General
While green tea polyphenols have been shown to inhibit the growth of human lung cancer cells in test tubes, few clinicial studies have investigated the link between green tea consumption and lung cancer in people and even these studies have been conflicting. One population-based clinical study found that Okinawan tea (similar to green tea but partially fermented) was associated with decreased lung cancer risk, particularly among women. A second clinical study revealed that green tea and black tea significantly increased the risk of lung cancer. As with colon and esophageal cancers, further clinical studies are needed before researchers can draw any conclusions about green tea and lung cancer.
Green Tea & Lung Cancer - Culture Study
A study using human lung cancer cell culture found that a combination of catechins rather than epigallocatechin gallate alone was more effective at producing apoptosis (programmed cell death), and the effect was synergistically increased when catechins were combined with other anti-cancer agents such as tamoxifen (a protein kinase antagonist). This provides additional support for the multi-agent approach to cancer. Smoking may cause damage to the DNA of various cells, including lymphocytes. One type of damage is sister-chromatid exchange (SCE). SCE rates were found to be elevated in smokers who did not consume green tea. Those smokers who did consume green tea had SCE rates comparable to those of nonsmokers, in spite of the fact that their average daily intake was only 3 cups per day. Coffee failed to show a protective effect. An animal study, however, did show that caffeine is an important chemopreventive agent in lung cancer protection, and that black tea also has an 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