Green tea is recommended for breast cancer
Like black tea, green tea is made by adding hot water to the cured leaves of the Camellia sinensis plant. Green tea leaves are unoxidized, whereas black tea leaves have been allowed to oxidize. White tea is made from uncured and unoxidized tea leaves of the same plant. Black tea and herbal teas such as yerba maté and chamomile, mint, sage, and Essiac™ tea are covered in other web pages. Green tea has been shown to have antioxidant, anti-inflammatory, and antihypertensive properties and may reduce the risk of stroke. Green tea may improve glucose metabolism and has been shown to support weight loss by suppressing hunger, increasing satiety, and increasing energy expenditure and fat oxidation. Green tea consumption has been found to be associated with increased bone mineral density and may help prevent osteoporotic fractures in older women. Increased consumption of green tea may reduce the risk of liver disease, although it appears not to reduce the risk of liver cancer. Consumption of tea has been found to be associated with reduced risks of melanoma and adult leukemia, as well as gastric, ovarian, endometrial, colorectal, and prostate cancer.Breast cancer-related effects of drinking green tea
Green tea contains catechins and other polyphenols that are thought to be responsible for its anti-cancer properties. Important green tea polyphenols include epigallocatechin-3-gallate (EGCG), epicatechin, epigallocatechin, and epicatechin-3-gallate. EGCG has been shown to inhibit tumor growth and angiogenesis of estrogen receptor positive (ER+) breast cancer in mice without affecting normal tissue growth. EGCG also has been found to inhibit growth and induce apoptosis of HER2-positive breast cancer cells, including those resistant to Herceptin.
EGCG has been shown to synergistically enhance the growth inhibition of ER+ cells by tamoxifen and Taxol (paclitaxel), thereby increasing the effectiveness of such therapy. In addition, green tea extract has been found to protect against tamoxifen-induced liver injury in rats. Green tea intake has been found to enhance the inhibitory effects of doxorubicin in Ehrlich ascites carcinoma tumor-bearing mice and in ovarian cancer cells. Finally, green tea polyphenols have been shown to have potentiating effect on cisplatin chemotherapy in a mouse cervical cancer model (cisplatin is sometimes used to treat triple negative (ER-, PR-, HER2-negative) breast cancer).
Numerous population studies have found that heavy green tea consumption is associated with lower risk of breast cancer. There is also some evidence that green tea consumption might help prevent recurrence in early stage (stages I and II) breast cancers.
Additional comments
Green tea consumption has been found to further reduce the risk of breast cancer associated with high dietary intake of mushrooms. In other words, there appears to be a synergistic effect between green tea and mushroom intake in reducing breast cancer risk.
Drinking very hot green tea (or very hot tea of any type) should be avoided. Rates of esophageal cancer are high in areas of the world where tea normally is consumed at high temperatures. In one study, the risk of esophageal cancer was found to be eight times higher for those who regularly drank very hot tea compared to those who drank warm or lukewarm tea. Note that it is the hot temperature that contributes to esophageal cancer, not the compounds found in green tea. In fact, one large Chinese population study found that relatively high urinary levels of green tea polyphenols were associated with lower risk of esophageal squamous cell cancer. Green tea should be prepared with hot, but not boiling, water to maximize its polyphenol content.
Green and black tea consumption decreases the bioavailability of folic acid in the diet by reducing the level of intestinal absorption and interfering with the folate pathway. This folate cycle inhibition is thought by some researchers to be one mechanism by which green tea protects against breast cancer. Similarly, tea inhibits iron absorption and high levels of iron in benign breast tissue has been found to be associated with increased risk of subsequent breast cancer. For those who require additional folate or iron, however, vitamin pills or other supplements containing folate or iron should not be taken with tea.
Prepared green or black tea contains less than half the caffeine of the same amount of drip coffee. However, high caffeine intake may increase the risk of benign breast disease, particularly atypical hyperplasia, which is associated with increased breast cancer risk. Those sensitive to caffeine or with benign breast disease should take steps to limit their caffeine intake when preparing green tea (e.g., by using loose green tea leaves instead of tea bags and discarding the first infusion).
People with a history of kidney stones normally are advised to avoid drinking black tea, since such consumption has been shown to increase the risk of kidney stone formation due to tea's oxalate content. Generally speaking, green tea has less than 20 percent of the oxalate content of black tea and may be safe to consume in moderate amounts for some patients (check with your urologist).
Selected studies
(-)-Epigallocatechin-3-gallate downregulates Pg-P and BCRP in a tamoxifen resistant MCF-7 cell line Phytomedicine, April 2010The present study was designed to investigate the anticancer activities of (-)-Epigallocatechin-3-gallate (EGCG) treatment in tamoxifen-resistant breast cancer cells (MCF-7Tam cells). The authors examined the effects of EGCG treatment on three plasma membrane proteins (Multidrug Resistance Protein (MRP1), P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP)) involved in drug resistance in order to uncover the molecular mechanisms involved. EGCG treatment (10-100 μg/ml for 24-72 hours) was found to inhibit cell growth and cause dose-dependent apoptosis (after treatment with 100 μg/ml EGCG for 24 hours, Bax expression increased and Bcl2 expression declined (p<0.05)). In addition, annexin V-FITC apoptosis assay found a significant increase in labeled cells (p<0.05). EGCG was found not to affect MRP1. However, administration of 100 μg/ml EGCG resulted in P-gp decrease to 53% of control cells (p<0.001) and this was not caused by downregulation of P-gp gene expression. EGCG induced a decline in P-gp even when MG132 (a strong proteasome inhibitor) was administered together with EGCG to MCF-7Tam cells. EGCG treatment also was found to inhibit BCRP activity: mRNA transcription and protein level were not influence by the treatment, but mitoxantrone testing found a strong inhibition of BCRP activity (p<0.001). In summary, EGCG downregulates the activity of two molecules that play a key role in drug metabolism and transport and that are highly expressed in tamoxifen-resistant breast cancer cells. The authors conclude that the interaction of EGCG with drugs used to treat estrogen-sensitive breast carcinoma and the potential use of EGCG in other drug-resistant diseases should be studied.
Grape seed proanthocyanidin suppression of breast cell carcinogenesis induced by chronic exposure to combined 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo[a]pyrene Molecular Carcinogenesis, February 2010
The present study was designed to investigate the chemopreventive activity of grape seed proanthocyanidin extract in breast cancer cells. Dietary prevention is a cost-efficient strategy to reduce the risk of breast cancer. Grape seed proanthocyanidins are candidates for the prevention of human breast cancer associated with long-term exposure to environmental carcinogens. In the study, the activity of grape seed proanthocyanidin extract in suppressing cellular carcinogenesis induced by repeated exposures to low doses of environmental carcinogens was examined. A combination of the carcinogens 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P) were used at picomolar concentrations to repeatedly treat noncancerous human breast epithelial MCF10A cells. This treatment would be expected to induce reduced dependence on growth factors, anchorage-independent growth, and acinar-conformational disruption, all cancer-related cellular changes. Therefore, these properties were used as biological target endpoints in assessing the ability of grape seed proanthocyanidin extract to suppress combined NNK- and B[a]P-induced precancerous cellular carcinogenesis. The minimum (noncytotoxic) concentration of grape seed proanthocyanidin extract required for suppressing precancerous cellular carcinogenesis was identified. The authors found that hydroxysteroid-11-beta-dehydrogenase 2 (HSD11B2) may have a role in NNK- and B[a]P-induced precancerous carcinogenesis, and that its expression may act as a molecular target endpoint in grape seed proanthocyanidin extract's suppression of such carcinogenesis. In addition, the authors determined that the ability of grape seed proanthocyanidin extract to reduce gene expression of cytochrome-P450 enzymes CYP1A1 and CYP1B1 (which can bioactivate NNK and B[a]P) might contribute to the chemopreventive actions of the extract. The authors conclude that grape seed proanthocyanidin extract may be effective in preventing human breast cell carcinogenesis induced by repeated exposures to low doses of multiple environmental carcinogens.
Urinary polyphenols and breast cancer risk: results from the Shanghai Women's Health Study Breast Cancer Research and Treatment, August 2009
The present study was designed to investigate the associations between risk of breast cancer and urinary excretion rates of polyphenols, including tea polyphenols. Polyphenols are the most abundant dietary antioxidants and have also been shown to have other anticancer activities. Measurement of polyphenol metabolites in the urine could complement dietary questionnaires and food component data in assessing the bioavailability of these nutrients. The study included 353 incident breast cancer cases and 701 individually matched controls nested within the Shanghai Women's Health Study cohort of women aged 40 to 70 years old at baseline. Mass spectrometry was used to measure urinary levels of tea polyphenols (epicatechin, epigallocatechin, and their metabolites) and flavonols (e.g., quercetin and kaempferol). Multivariate conditional logistic regression analyses were used to calculate associations between urinary excretion rates of the various polyphenols and risk of breast cancer. Urinary excretion of tea polyphenols was found to increase with increasing tea consumed among the controls, but not among the women with breast cancer. Compared with the breast cancer cases, the controls were found to have higher urinary levels of total polyphenols and tea polyphenols, particularly epicatechin. On the other hand, no dose-response relationship was found between total urinary polyphenols and risk of breast cancer. However, urinary excretion of epicatechin was found to be inversely associated with breast cancer risk (odds ratio = 0.59, 95% confidence interval = 0.39-0.88 for the intermediate tertile). In spline regression, an overall dose-response relationship was found between epicatechin level and risk of breast cancer, although it was not observed in low and middle urinary excretion range. The authors conclude that high urinary epicatechin levels may be related to a reduced risk of breast cancer.
Drinking Green Tea Modestly Reduces Breast Cancer Risk Journal of Nutrition, February 2009
The present Chinese case-control study was designed to assess the association between regular green tea consumption and risk of breast cancer. Green tea is a common beverage in China. Previous epidemiological and animal studies have found that tea and tea polyphenols may have preventive activities against various types of cancer, including breast cancer. Catechol-O-methyltransferase (COMT) catalyzes both catechol estrogens and tea polyphenols. The COMT rs4680 AA genotype results in lower COMT activity. Therefore, the COMT rs4680 genotype may influence the association between green tea consumption and breast cancer risk. The study included 3,454 incident breast cancer cases and 3,474 controls aged 20 to 74 years in Shanghai, China during the period 1996 to 2005. All of the study participants were interviewed in person about green tea intake, including first age of green tea consumption, duration of use, brew strength, and quantity. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for green tea intake and adjusted for age and other confounding factors. Compared with women who did not drink green tea, regular green tea drinkers were found to have a modestly lower risk of breast cancer (OR = 0.88; 95% CI: 0.79–0.98). Among premenopausal women, increasingly reduced risk also was observed for increasing years of green tea drinking (P-trend = 0.02) and a dose-response relationship with amount of tea consumed per month was also found (P-trend = 0.046). The COMT rs4680 genotype turned out not to have a modifying effect on the association between green tea intake and breast cancer risk. The authors conclude that drinking green tea may be weakly associated with a reduced risk of breast cancer.
EGCG stabilizes p27kip1 in E2-stimulated MCF-7 cells through down-regulation of the Skp2 protein Endocrinology, December 2008
The current study was conducted to investigate the mechanisms involved in epigallocatechin-3-gallate's (EGCG's) inhibition of the growth of estrogen-responsive (ER+) MCF-7 human breast cancer cells. EGCG is a component of green tea. Loss of p27Kip1 has been found to be associated with a poor prognosis in breast cancer. A decline in p27Kip1 levels is mainly the result of enhanced proteasome-dependent degradation mediated by the specific ubiquitin ligase subunit S-phase kinase protein 2 (Skp2). EGCG has been found to stabilize p27Kip1 levels in breast cancer cells, but whether this effect is mediated through changes in Skp2 expression has been unclear. In the study, EGCG was found to increase p27Kip1 and decrease Skp2 in a time- and dose-dependent manner. These findings suggest that p27Kip1 and Skp2 may be involved in EGCG's growth inhibition in MCF-7 cells. Of note was the result that mRNA levels of p27Kip1 and Skp2 did not change significantly in estrogen-stimulated MCF-7 cells after EGCG treatment. Furthermore, overexpression of Skp2 in MCF-7 cells prevented the accumulation of p27Kip1 and promoted resistance to the antiproliferative effects of EGCG, suggesting that the down-regulation of Skp2 is the mechanism underlying p27Kip1 accumulation. In addition, both tamoxifen and paclitaxel significantly and synergistically enhanced the growth inhibition of MCF-7 cells by EGCG through the down-regulation of Skp2 protein. However, the down-regulation of Skp2 was not always correlate with the up-regulation of p27, suggesting that EGCG-dependent Skp2 down-regulation can influence cell growth in several ways. The therapeutic strategies designed to reduce Skp2 may therefore play an important clinical role in treatment of breast cancer cells.
Caffeine consumption and the risk of breast cancer in a large prospective cohort of women Archives of Internal Medicine, October 2008
In this prospective study, the association between caffeine consumption and breast cancer risk in 38,432 women 45 years or older and enrolled in a completed cancer prevention trial was studied. The women were cancer free at baseline (1992-1995), when detailed dietary information was collected from them. There were 1,188 invasive breast cancer cases during a mean follow-up period of ten years. Consumption of caffeine, caffeinated beverages and caffeinated foods was found not to be significantly associated with overall risk of breast cancer. Multivariate relative risks (RRs) of breast cancer were found to be 1.02 (95% confidence interval [CI]: 0.84-1.22) for caffeine (top vs. bottom quintile), 1.08 (CI: 0.89-1.30) for coffee (greater or equal to four cups daily vs. almost never), and 1.03 (CI: 0.85-1.25) for tea (greater than or equal to two 2 cups daily vs. almost never). However, for women with benign breast disease, a borderline significant positive association with breast cancer risk was found for the highest quintile of caffeine consumption (RR = 1.32; CI: 0.99-1.76). In addition, for the highest coffee consumption (greater than or equal to four cups per day), tests for interaction were marginally significant (1.35; CI: 1.01-1.80). Caffeine consumption was also found to be significantly positively associated with the risk of estrogen and progesterone receptor negative (ER-,PR-) breast cancer (1.68; CI: 1.01-2.81) and with breast tumors larger than two cm (1.79; 1.18-2.72). While the data showed no overall association between caffeine consumption and breast cancer risk, they indicate the possibility of increased risk in women with benign breast disease for tumors that are estrogen and progesterone receptor negative or larger than 2 cm.
Dietary intakes of mushrooms and green tea combine to reduce the risk of breast cancer in Chinese women International Journal of Cancer, October 2008
The present southeast China case-control study was designed to investigate the effect of dietary mushroom intake and the joint effect of mushrooms and green tea on the risk of breast cancer. The study, conducted during 2004-2005, included 1,009 women with breast cancer aged 20 to 87 years old. Also included were 1,009 age-matched controls, who were healthy women randomly recruited from outpatient breast clinics. Data on the frequency and quantity of mushroom and green tea consumption, usual diet, and lifestyle factors were obtained with face-to-face interviews using a validated questionnaire. Compared with those who did not consume any mushrooms, the odds ratios (ORs) were 0.36 (95% CI = 0.25-0.51) and 0.53 (0.38-0.73) for daily consumption of 10 g fresh mushrooms and 4 g dried mushrooms, respectively, adjusting for potential confounders. The inverse relationship between mushroom consumption and breast cancer risk was found to be dose-dependent (p < 0.001) and was found for both premenopausal and postmenopausal women. Compared to those with no mushroom or green tea intake, the ORs were 0.11 (0.06-0.20) and 0.18 (0.11-0.29) for those with both high daily intake of fresh or dried mushrooms and regular green tea consumption (made from 1.05 g dried green tea leaves per day). The related linear trends were statistically significant for joint effect (p < 0.001). The authors conclude that high dietary intake of mushrooms decreased breast cancer risk in Chinese women and that green tea consumption further decreased the risk of breast cancer.
Green tea intake, MTHFR/TYMS genotype and breast cancer risk: the Singapore Chinese Health Study Carcinogenesis, July 2008
The present study was designed to test the hypothesis that the mechanism of cancer prevention of the green tea polyphenol (–)-epigallocatechin-3-gallate (EGCG) is through folate pathway inhibition. EGCG previously has been reported to prevent cancer in experimental studies by means of folate pathway inhibition. The authors proposed that if folate pathway inhibition is the EGCG cancer preventive mechanism, then the protective effect of green tea consumption against breast cancer would be stronger among women with low dietary folate intake and among those with high-activity methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TYMS) genotypes. In a nested case-control study of 380 breast cancer cases and 662 controls within the Singapore Chinese Health Study, among women with low folate intake (<133.4 µg/day), weekly/daily green tea consumption was found to be inversely associated with breast cancer risk (i.e., compared with low green tea intake) (odds ratio (OR) = 0.45, 95% confidence interval (CI) = 0.26–0.79, P for interaction = 0.02). Among women with higher folate intake (>133.4 µg/day), green tea intake was not found to be associated with breast cancer risk. Similarly, among women possessing high-activity MTHFR/TYMS genotypes (0–1 variant allele), weekly/daily versus less frequent green tea intake was found to be associated with lower breast cancer risk (OR = 0.66, 95% CI = 0.45–0.98). This association was even stronger for those women who also had low folate intake (OR = 0.44, 95% CI = 0.22–0.89) compared to those with a high folate intake (OR = 0.92, 95% CI = 0.55–1.54). Furthermore, this association was not found among women possessing the low-activity genotypes (2–4 variant alleles). The authors conclude that folate pathway inhibition may be one mechanism through which green tea protects against breast cancer.
Chemopreventive effect of green tea extract and tamoxifen on mouse mammary preneoplastic lesions American Association for Cancer Research (AACR) Meeting, April 2008
The present study was designed to investigate the chemopreventive effect of green tea extract and tamoxifen, alone and in combination, on mammary cancer in a mouse model. Green tea catechins, including (-)-epigallocatechin gallate, may have a role in the chemoprevention of cancer; reduced rates of gastric cancer have been found among people with a habit of frequent green tea drinking. In the study, mammary carcinogenesis and preneoplastic lesions (hyperplastic alveolar nodules) were induced in C3H/OuJ mouse. The mice were divided into five groups: (1) control (no treatment); (2) 1% green tea extract orally administered in drinking water; (3) 0.5% green tea extract orally administered in drinking water; (4) tamoxifen pellets administered subcutaneously (10mg /body/3months); and (5) 1% green tea extract and tamoxifen in combination. Treatments were initiated at 10 weeks of age and tumor formation was observed and recorded. The mice were sacrificed at 48 weeks old and the mammary glands were removed and stained to obtain counts of hyperplastic alveolar nodule and Nucleolar Organizer Regions (AgNORs). The tumor incidences of groups (1) through (5) were found to be 30%, 25%, 25%, 14% and 0%, respectively, but these results were not significantly different. The average hyperplastic alveolar nodules counts of the control group, 1% green tea extract group, 0.5% green tea extract group, tamoxifen group and combination group were 9.2, 6.1, 7.5, 6.0 and 5.8, respectively. Hyperplastic alveolar nodules formation was found to be significantly reduced in the 1% green tea extract, tamoxifen and combination groups compared with the control group. The mean AgNOR count of the control, 1% green tea extract, 0.5% green tea extract, tamoxifen and combination groups were 2.86, 1.89, 1.99, 1.70 and 1.60 per cell, respectively. AgNOR formation was significantly reduced in the 1% green tea extract, tamoxifen and combination groups compared with the control group. The authors conclude that green tea extract and tamoxifen have some potential in the chemoprevention of breast cancer, individually and in combination.
Trastuzumab-Resistant HER2-Driven Breast Cancer Cells Are Sensitive to Epigallocatechin-3 Gallate Cancer Research, October 2007
The purpose of the present study was to evaluate the effect of treatment with the green tea polyphenol epigallocatechin-3 gallate (EGCG) on trastuzumab-resistant breast cancer cells. EGCG is the major polyphenol found in green tea. Overexpression of the epidermal growth factor receptor HER2 is found in 30% of breast cancers. Trastuzumab (Herceptin) has proven highly successful in treating HER2 tumors when used in combination with other chemotherapeutic agents. However HER2 tumors can develop resistance to trastuzumab or metastasize to the brain, which is inaccessible to antibody therapy that cannot cross the blood-brain barrier. The authors previously demonstrated that EGCG inhibits growth and transformed phenotype of HER2 mouse mammary tumor cells. In the current study, EGCG treatment was applied to trastuzumab-resistant BT474 human breast cancer cells (isolated by chronic trastuzumab exposure) and JIMT-1 breast cancer cells (derived from a patient who displayed clinical resistance to trastuzumab). EGCG was found to result in a dose-dependent inhibition of growth and cellular ATP production, and apoptosis at high concentrations. The authors conclude that EGCG in combination with trastuzumab might provide a new strategy for treatment of HER2-overexpressing breast cancers, given that EGCG has the ability to cross the blood-brain barrier.
Combined effect of green tea and Ganoderma lucidum on invasive behavior of breast cancer cells International Journal of Oncology, April 2007
The present study was designed to evaluate any potential interaction between the anticancer effects of green tea and the reishi mushroom (Ganoderma lucidum) against breast cancer cells. Epidemiological studies have demonstrated that consumption of green tea may reduce the risk of a variety of cancers and the reishi mushroom has long been used for the treatment of cancer in traditional Chinese medicine. In the study, green tea and reishi mushroom extracts were each shown to independently inhibit adhesion, migration and invasion of (ER-/PR-) MDA-MB-231 breast cancer cells. Adding green tea extract was found to enhance the antiproliferative effect of the reishi mushroom extract, as well as reducing colony formation of breast cancer cells. This effect was mediated by the down-regulation of expression of oncogene c-myc in MDA-MB-231 cells. In other words, green tea and reishi mushroom extracts each inhibited adhesion, migration and invasion of MDA-MB-231 cells, and their combination demonstrated a synergistic effect.
Green tea, black tea and breast cancer risk: a meta-analysis of epidemiological studies Carcinogenesis, July 2006
The present meta-analysis was designed to examine the associations between green tea and black tea drinking and breast cancer risk. The analysis included 13 population studies in eight countries that provided data on intake of green tea, black tea, or both in relation to risk of breast cancer. Summary odds ratios (ORs) for highest versus lowest or non-tea consumption level were estimated based on fixed and random effects models. Q statistics were used to examine heterogeneity between studies. With respect to green tea, the combined results from the four relevant studies indicated a reduced risk of breast cancer for the highest versus non/lowest intake (OR = 0.78, 95% CI = 0.61–0.98). However, conflicting results were observed for black tea in case-control compared to cohort studies. The combined results from the eight relevant case-control studies found a small reduction in breast cancer risk associated with black tea intake (OR = 0.91, 95% CI = 0.84–0.98). This inverse association was found to be stronger in hospital-based (OR = 0.77, 95% CI = 0.50–1.19) than population-based case–control studies (OR = 0.94, 95% CI = 0.81–1.09). However, five cohort studies showed a small increase in breast cancer risk associated with black tea consumption (OR = 1.15, 95% CI = 1.02–1.31). The authors conclude that green tea consumption is associated with a lower risk of breast cancer. The available data also suggest a possible late-stage, promotional effect of black tea on breast carcinogenesis.
Study of the combined effect of X-irradiation and epigallocatechin-gallate (a tea component) on the growth inhibition and induction of apoptosis in human cancer cell lines Oncology Reports, 2004 12(1):159-167
The present study was designed to explore whether an antioxidant naturally present in food or beverages could promote apoptosis in cancer cells submitted to X-irradiation. Antioxidants are known to act as powerful scavengers of free-radicals. Free radicals are able to induce DNA strand breaks and oxidative modifications of DNA bases. Free radicals are not only produced naturally in cells following a stress or respiration but also following ionizing radiation. In the study, epigallocatechin gallate (EGCG), a potent antioxidant present in tea, was tested on three human cancer cell lines: HeLa (cervical carcinoma), K-562 (chronic myelogenous leukemia) and IM-9 (multiple myeloma). Cell proliferation, morphological changes, cell cycle effects and apoptosis were assessed. Irradiation alone was found to inhibit cancer cell proliferation and increase apoptosis, as well as increasing the appearance of polyploid cells in all three cell lines in a dose-dependent manner. IM-9 cells were found to be the most radiation sensitive, based on all the factors tested, and HeLa cells were the least radiation sensitive, while K-562 cells had an intermediate level of sensitivity to radiation. EGCG was found to have no effect on cell proliferation, while inducing a dose-dependent increase of apoptosis in the three cell lines. IM-9 cells again were the most sensitive to this effect, while HeLa and K-562 cells were somewhat less sensitive. Combined treatment with X-irradiation and EGCG resulted in a significant increase in apoptosis, correlated with a decrease of proliferation, in IM-9 and K-562 cells and to a lesser extent, in HeLa cells, when compared to either EGCG or ionizing radiation alone. The authors conclude that these preliminary results show that EGCG can act as a radiation enhancer in cancerous cell lines.
