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:
Breast Cancer: General
Clinical studies in animals and test tubes suggest that polyphenols in green tea inhibit the growth of breast cancer cells. In one study of 472 women with various stages of breast cancer, researchers found that women who consumed the most green tea experienced the least spread of cancer (particularly premenopausal women in the early stages of breast cancer). They also found that women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to suffer recurrences of the disease after completion of treatment. However, women with late stages of breast cancer experienced little or no improvement from drinking green tea. In terms of breast cancer prevention, the studies are inconclusive. In one very large study, researchers found that drinking tea, green or any other type, was not associated with a reduced risk of breast cancer. However, when the researchers broke down the sample by age, among women under the age of 50, those who consumed 3 or more cups of tea per day were 37% less likely to develop breast cancer compared to women who didnt drink tea.
Green Tea Shown To Possess Antitumor Effect In Breast Cancer
ScienceDaily (Dec. 9, 2007) — A team of scientists led by Dr. Radha Maheshwari, professor of Pathology at the Uniformed Services University of the Health Sciences (USU) and Rajesh Loganathan Thangapazham, a graduate student, have shown that green tea has antitumor effect in breast cancer cells. Cancer is a disease caused by the increased proliferation of cells which group and form a lump called tumor. Tumors can be benign or malignant. Cells from malignant tumors break away from the original tumor and spread to other parts of the body growing and forming new tumors. They can invade, penetrate into blood and lymphatic vessels, circulate via the bloodstream and can grow in a normal organ or tissue anywhere in the body. Unfortunately treatment options for metastasis are very limited and usually represent the end stage of the disease. Unlike malignant tumors, benign tumors do not invade and, with very rare exceptions, are not life threatening. Chemoprevention broadly implies the use of a chemical substance of either natural or synthetic origin, to prevent, hamper, arrest or reverse a disease. Phytochemicals are plant based non nutritive components with substantial medicinal properties. Dr. Maheshwari’s study observed that green tea can inhibit the invading capacity of these breast cancer cells and have also identified the mechanisms involved in death inducing and invasion inhibiting effects of green tea. Epidemiological studies also suggest that the risk of breast cancer is found to be less in Asian countries consuming green tea. These studies have greater clinical significance since the ability of these phytochemicals to activate anti-cancer program of tumor cells might determine the success of chemotherapy. The recently concluded study will be published in the Journal of Cancer Biology and Therapy, December 2007, Volume 6, Issue 12. A study by Dr. Maheshwari that was published earlier this year in Cancer Letters showed that green tea is effective in delaying tumor incidence as well as in reducing the tumor burden. Green tea was found to inhibit growth of tumors as well as induce death of breast cancer cells.
Green Tea and Breast Cancer: Japan Study
A Japanese study of 472 women with various stages of breast cancer explored in greater detail the epidemiological findings on green tea's protection against breast cancer. In this case, women with stage I, II and III breast cancer were assessed in terms of their green tea consumption. It was found that "premenopausal women who consumed more green tea had a lower number of lymph node metastases. In postmenopausal women greater consumption of green tea correlated with increased expression of the estrogen and progesterone receptor, which implies more differentiated tumor cells and better prognosis." Finally, in a seven-year follow it was found that "women with stage I or II cancer who consumed five or more cups of green tea a day had approximately half the recurrence rate of those women who consumed four cups or less." Researchers at the Department of Surgery, Division of Oncology and. Center for Human Nutrition, University of California found that Inhibition of VEGF transcription appeared to be one of the molecular mechanism(s) involved in the antiangiogenic effects of green tea, which may contribute to its potential use for breast cancer treatment and/or prevention. One way in which green tea helps protect against breast cancer is by enhancing glucuronization of estrogens in the liver, a process through which estrogens are rendered inactive by being conjugated with glucuronic acid, a form in which they are excreted from the body. Perhaps it is mainly this mechanism that also accounts for lower estradiol levels found in those Japanese women who consume a significant amount of green tea. (Another mechanism might involve higher levels of sex hormone binding globulin found in women who consume green tea; the authors caution, however, that this might be due to caffeine.)
Green Tea and Breast Cancer: Animal Study
Besides human epidemiological studies, we also have experimental animal studies showing that green tea catechins provide significant protection against breast cancer. One study found that after exposure to a strong mammary carcinogen (DMBA), the survival rate in the group of rats fed a diet enriched with 1% green tea catechins was 93.8%, compared with only 33.3% in the control group. The tumors in the green tea group were also significantly smaller.
References: Life Extension Magazine and other studies added.
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