November 5, 2009
Although scientists are reluctant to endorse green tea as a cancer prevention method, evidence continues to grow regarding the chemically complex drink’s potential benefits - including results of a new randomized, controlled trial by researchers at University of Texas M. D. Anderson Cancer Center, which suggest it had some inhibiting effect in patients with a pre-malignant condition known as oral leukoplakia.
As reported in a report published online Nov 5 by Cancer Prevention Research(1), a team headed by Vassiliki Papadimitrakopoulo, MD, professor of medicine in M.D. Anderson’s Department of Thoracic/Head and Neck Medical Oncology, tested green tea extract taken orally for three months by 41 patients diagnosed with oral leukoplakia and therefore at high risk of developing oral cancer.
The patients were divided into cohorts taking either placebo or one of three different doses of green tea extract 500 mg/m2, 750 mg/m2 or 1,000 mg/m2 [mg/m2 refers to milligrams per meter squared of body mass – calculated by a formula using height and weight to reflect a person’s relative size].
The researchers assessed clinical response in oral pre-malignant lesions and found:
• 58.8% of patients at the highest doses displayed clinical response,
• Compared with 18.2% among those taking placebo.
They also observed:
• A trend toward improved histology [cell & tissue integrity],
• And a trend towards improvement in a handful of biomarkers that may be important in predicting cancer development.
Patients were followed for 27.5 months and at the end of the study period, 15 developed oral cancer.
• Although there was no difference in oral cancer development overall between those who took green tea and those who did not,
• Patients who presented with mild to moderate dysplasia [abnormal cell growth] had a longer time to develop oral cancer if they took green tea extract.
Although encouraged by the results, Dr. Papadimitrakopoulo cautioned against any recommendations that green tea could definitely prevent cancer.
“This is a phase II study with a very limited number of patients who took what would be the equivalent of drinking eight to 10 cups of green tea every single day,” she said. “We cannot with certainty claim prevention benefits from a trial this size.”
Dong Shin, MD, (professor of hematology and medical oncology at Emory School of Medicine, and a Cancer Prevention Research editorial board member) agreed, but said this trial is certainly a step in the right direction. “A clinical trial with a natural compound is no easy task, and these researchers have accomplished that,” Dr. Shin stated in a companion article commenting on the trial(2). “The lack of toxicity is also important because often when you give supplements at higher doses than what would occur naturally, you induce nausea and vomiting. That did not happen in this trial.”
Neither researcher had a reason why patients concerned about cancer should not drink green tea, but they cautioned against relying on the beverage to definitively reduce their risk of cancer.
“The goal of this kind of research is to determine whether or not these supplements have long-term prevention effects," said Dr. Papadimitrakopoulou. "More research - including studies in which individuals at high risk are exposed to these supplements for longer time period - is still needed to answer that sort of question.”
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Cited Articles:
1. “Phase II Randomized, Placebo-Controlled Trial of Green Tea Extract in Patients with High-Risk Oral Premalignant Lesions”
2. “Oral Cancer Prevention Advances with a Translational Trial of Green Tea”
Sources:
• American Association for Cancer Research (which publishes Cancer Prevention Research) news release Nov 5, 2009
• University of Texas M. D. Anderson Cancer Center news release Nov 5, 2009
Note: This information has not been evaluated by the FDA. It is general and is not meant to prevent, diagnose, treat or cure any illness, condition, or disease. It is very important that you make no change in your healthcare plan or health support regimen without researching and discussing it in collaboration with your professional healthcare team.
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