First Clinical Study Shows 90 Percent Efficacy in Men with Pre-malignant Lesions
April 20, 2005. Anaheim, Calif. - After a year's oral administration of green tea catechins (GTCs), only one man in a group of 32 at high risk for prostate cancer developed the disease, compared to nine out of 30 in a control, according to a team of Italian researchers from the University of Parma and University of Modena and Reggio Emilia led by Saverio Bettuzzi, Ph.D.
Their results were reported here today at the 96 th Annual Meeting of the American Association for Cancer Research.
"Numerous earlier studies, including ours, have demonstrated that green tea catechins, or pure EGCG (a major component of GTCs), inhibited cancer cell growth in laboratory models," Bettuzzi explained. "We wanted to conduct a clinical trial to find out whether catechins could prevent cancer in men. The answer clearly is yes."
Earlier research demonstrated primarily that green tea catechins were safe for use in humans. Bettuzzi and his colleagues had found that EGCG targets prostate cancer cells specifically for death, without damaging the benign controls. They identified Clusterin, the most important gene involved in apoptosis, or programmed cell death in the prostate, as a possible mediator of catechins action. "EGCG induced death in cancer cells, not normal cells, inducing Clusterin expression" said Bettuzzi.
To gauge susceptibility for prostate cancer among their research subjects, the team of Italian scientists recruited men with high-grade prostatic intraepithelial neoplasia - premalignant lesions that presage invasive prostate cancer within one year in nearly a third of cases and for which no treatment was given.
Eligible men were between 45 and 75 years of age. Vegetarians and men consuming green tea or derived products, or those taking anti-oxidants or following anti-androgenic therapy were excluded.
Of the 62 volunteers, 32 received three tablets per day of 200 mg each GTCs; the remainder were given a placebo. Follow-up biopsies were administered after six months and again at one year. Only one case of prostate cancer was diagnosed among those receiving 600 mg daily of GTCs, while nine cases were found in the untreated group. The 30 percent incidence rate among controls is consistent with previous findings, as was the absence of significant side effects or adverse reactions.
The interest in green tea catechins and other polyphenols - antioxidants found in many plants that give some flowers, fruits and vegetables their coloring - derives from traditional Chinese medicine, and the observation of lower cancer rates among Asian populations.
Bettuzzi observed that the Mediterranean diet is rich in vegetables, and lower rates of prostate cancer are found in that region, as well.
The 600 mg-per-day dosage of caffeine-free, total catechins (50 percent of which is EGCG) given to participants in the Italian study is one or two times the amount of green tea consumed daily in China, where ten to 20 cups a day is normal.
"We still don't know enough about the biological processes leading to prostate cancer," Bettuzzi noted. "The only thing we know for sure is that prostate cancer is diffuse, related to age and more prevalent in the West. Thus, prevention could be the best way to fight it. Although our follow-up will continue for up to five years, a larger, confirmatory study is needed."
Even so, Bettuzzi hints at the exciting prospect of using green tea catechins as a prophylactic against prostate cancer in men believed to be at higher risk, such as the elderly, African-Americans, and those with a family history of prostate cancer. https://www.psa-rising.com/eatingwell...vention05.html
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For now we see through a glass, darkly.... 1st Corinthians 13:12
Green tea has been consumed for thousands of years, and many claims regarding the health-promoting properties of this ancient beverage have been made over the millennia. However, we are just beginning to scratch the surface of green tea�s potential to aid in disease prevention and treatment through the use of modern laboratory and clinical research methods. While many of the fantastic claims being made for green tea are, doubtless, unlikely to be true, recent research has shown a surprising array of potentially beneficial effects associated with a group of compounds found in green tea. Green tea polyphenols, and epigallocatechins and epicatechins in particular, have especially piqued the interest of researchers looking at ways to improve the prevention and treatment of both cardiovascular disease and cancer. Unfortunately, most of the available research data for green polyphenols has been derived from low-powered dietary survey-based studies, or from laboratory studies of green tea extracts and their effects on cells artificially grown in culture dishes.
Now, a newly published clinical research study in the journal Cancer Prevention Research offers some intriguing insights into some potentially important clinical effects of green tea polyphenols in men with newly diagnosed prostate cancer.
In this small pilot study, 26 men with newly diagnosed prostate cancer took daily supplements of green tea polyphenols while they were awaiting prostate cancer surgery (1.3 grams of polyphenols per day). At both the beginning and the end of this short-term study, blood was drawn to assess for tumor markers known to be associated with the stage and extent of prostate cancer (the study was concluded for these patients, individually, on the day that each underwent prostate cancer surgery). Additionally, cancer-associated fibroblast cells, which are often associated with multiple different types of cancer, and which are thought to secrete proteins that directly and indirectly increase tumor growth, were cultured in laboratory dishes, and then treated with green tea polyphenols. Changes in tumor-stimulating proteins from these prostate cancer-associated fibroblasts cells were then measured following polyphenol treatment.
Prostate-specific antigen (PSA), which is uniquely secreted by both normal and malignant prostate gland cells, is the most commonly used blood marker for prostate cancer. As prostate cancer progresses, PSA levels in the blood will rise in the vast majority of men with this disease. When prostate cancer is successfully treated, PSA levels will trend back towards normal levels. (Rising PSA levels following previous prostate cancer treatment almost always signify cancer recurrence.) Other important tumor-associated factors include vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These proteins are known to stimulate the growth and spread of many types of cancer, including prostate cancer. Other known adverse tumor growth factors include insulin-like growth factor (IGF), and IGF binding protein. All of these tumor growth factors were measured in the blood samples collected from these 26 men, both at the beginning of this brief study and at its conclusion.
When all of the data was analyzed, some tantalizing results were discovered. Blood levels of PSA, VEGF, HGF, IGF and IGF binding protein were all significantly decreased following a brief period of dietary supplementation with green tea polyphenols. Additionally, VEGF and HGF secretion by prostate cancer-associated fibroblasts significantly decreased, as well, following treatment of these cultured cells with green tea polyphenols.
While this brief and small pilot does not provide any direct proof that dietary supplementation with green tea polyphenols can prevent prostate cancer, or improve survival in patients already diagnosed with prostate cancer, it does offer indirect evidence, based upon a decrease in prostate cancer-associated tumor markers, that green tea polyphenols may be able to inhibit prostate cancer cell growth, and not only in cancer cells growing in a laboratory culture dish, but also in a living, breathing human being with prostate cancer.
The obvious next step is to conduct several large, long-term, prospective, randomized, placebo-controlled clinical research trials to put the findings of this small but intriguing pilot study to the test. Fortunately, there are several such clinical trials already underway. Until the results of these clinical trials are known, however, it remains unclear if green tea polyphenols are capable of reducing the risk of prostate cancer (or any other type of cancer), or the risk of dying from a previously diagnosed prostate cancer, to any clinically significant degree. When the data from these larger prospective clinical research trials become available, I will certainly provide an update in this important area of cancer prevention and treatment research.
Green Tea Shown to Prevent Prostate Cancer
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