Green Tea and Breast Cancer
EGCG Show Anti-Cancer Promise

Green tea is high in the antioxidant EGCG (epigallocatechin-3-gallate) which helps prevent the body’s cells from becoming damaged and prematurely aged. Studies have suggested that the combination of green tea and EGCG may also be beneficial by providing protection against certain types of cancers, including breast cancer.

A 2008 green tea and breast cancer study conducted by researchers at the University of Mississippi finds that consuming EGCG significantly inhibits breast tumor growth in female mice. These results bring us one step closer to a better understanding of the disease, and to potentially new and naturally occurring therapies.

Another 2009 black / green tea and breast cancer study conducted by researchers in University of Wisconsin found that drinking 3 or more cups of tea per day may reduce the risk of breast cancer in younger and possibly pre-menopausal women.

Regular exercise and green tea "may play an important role in the prevention of depression among breast cancer survivors," report Dr. Xiao Ou Shu of Vanderbilt University.

They examined depression-related factors in 1,399 Chinese women who were 54 years old on average and treated for breast cancer in Shanghai.

Six months after their diagnosis, the researchers assessed the women's physical activity levels; food, tea, and alcohol consumption; cigarette smoking; and use of herbal medicines and supplements.

The researchers discovered that women who exercised were up to 40% less likely to suffer from depression.

Tea drinkers were also 36% less likely to suffer from depression. The vast majority of the tea drinkers - 90 percent - drank green tea. The scientists concluded:

Drinking 3 or more cups of tea a day may help to reduce the risk of breast cancer in younger women.

Findings from a large case-control study in the US has found that women under the age of 50 who consumed modest amounts of tea had a 37% reduced risk of breast cancer compared to non-tea drinking women.

There is a great deal of in vitro (petri dishes) evidence showing that EGCG and theaflavin, two polyphenols found in green and black tea respectively, suppress mammary tumors. Green and black tea extracts also demonstrate antimutagenic, antiproliferative and antineoplastic activities in vitro.

However, population studies on the effects of green or black tea have been largely inconclusive. In the present study data from a large population-based, case-control study was examined with a view to shedding more light on the potential role of tea consumption.

Cases were women with a first primary breast cancer diagnosis identified from cancer registries in 3 US states. Age range at diagnosis was 20 - 74 years. A total of 5,059 cases were included in the analysis.

Overall 44.7% of cases reported ever drinking tea 5 years before diagnosis /reference date.

Women aged 50 or lower years who reported drinking 3 or more cups of tea per day, 5 years prior to the interview, had a 37% reduced BC risk compared with women reporting no tea consumption.

No similar associations were observed in the two other age groups: 51-65 years and older than 65 years.

This study has a number of limitations which may have affected the findings. As with all retrospective studies recall bias is a possibility, as women were being asked not only about tea consumption 5 years before diagnosis, but also about lifestyle factors and body weight which may be difficult to recall.

Furthermore a differentiation between green and black tea was not made. However the authors suggest that because of the time period of data collection (1998 and 2001), and as the majority of women were Caucasian, it can be assumed that the bulk of tea consumed would have been black tea.

While the findings from this large case-control study suggest that drinking 3 or more cups of tea per day may reduce the risk of breast cancer in younger and possibly pre-menopausal women, further studies are required to confirm these results.

Epidemiological studies suggest that green tea and its major constituent, EGCG, can provide some protection against cancer. Because these studies were very limited, the anti-cancer mechanism of green tea and EGCG was not clear.

As a result, the researchers examined whether drinking EGCG (just the antioxidant infused in water) inhibited the following: expression of VEGF (vascular endothelial growth factor, which is found in a variety of breast cancer types); tumor angiogenesis (thought to help tumors expand by supplying them with nutrients); and the growth of breast cancer in female mice.

Seven week old female mice were given EGCG (25 mg/50 ml) in drinking water for five weeks (approximately 50-100 mg/kg/day.) The control mice received regular drinking water. In the second week of the study mouse breast cancer cells were injected in the left fourth mammary glands of the mice.

Tumor size was monitored by measuring the tumor cross section area (TCSA). Tumors were eventually isolated and measured for tumor weight, intratumoral microvessel (IM) density (using staining), and VEGF protein levels (using ELISA).

At the end of the five week period the researchers found that oral consumption of EGCG caused significant decreases in TCSA (66%), tumor weight (68%), IM density 155±6 vs.111±20 IM#mm^2) and VEGF protein levels (59.0±3.7 vs. 45.7±1.4 pg/mg) in the breast tumors vs. the control mice, respectively (N=8; P<0.01). Further, VEGF plasma levels were lower in EGCG mice than in control mice (40.8±3.5 vs. 26.5±3.8 pg/ml P< 0.01).

Dr. Gu, the senior researcher for the study, hypothesized that the reason for the link between EGCG and the reductions in the cancer data was because EGCG directly targets both tumor blood vessels and tumor cells of breast cancer.  It suppresses new blood vessel formation in breast tumors, as well as the proliferation and migration of breast cancer cells.

Gu concluded by saying:

Dr. Gu will present his team’s green tea and breast cancer findings, entitled Oral Administration of EGCG, an Antioxidant Found in Green Tea, Inhibits Tumor Angiogenesis and Growth of Breast Cancer in Female Mice, at the 121st Annual Meeting of the American Physiological Society, part of the Experimental Biology 2008 scientific conference.

Xiaoli Chen, Wei Lu, Ying Zheng, Kai Gu, Zhi Chen, Wei Zheng, Xiao Ou Shu (2010). Exercise, Tea Consumption, and Depression Among Breast Cancer Survivors. Journal of Clinical Oncology, Vol 28, No 6 (February 20), 2010: pp. 991-998.

Kumar, N., Titus-Ernstoff, L., Newcomb, P. A., Trentham-Dietz, A., Anic, G. and Egan, K. M. (2009). Tea consumption and risk of breast cancer. Cancer Epidemiol. Biomarkers Prev. 18(1): 341-45.

Press Release 1 April 2008. American Physiological Society (APS). http://www.newswise.com/institutions/view/?id=1167

Breast Cancer. Breast-Plastic-Surgery.org.

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