(Ivanhoe Newswire) -- Evidence continues to brew about the protective
effects of green tea against cancer, but scientists are still not sure the
tea leaves reveal the answer.
Vassiliki Papadimitrakopoulo, M.D., professor of medicine in the Department
of Thoracic/Head and Neck Medical Oncology at the University of Texas M. D.
Anderson Cancer Center, and colleagues tested 41 patients who took green tea
extract orally for three months at three dose levels.
Nearly 60 percent of patients with oral pre-malignant lesions, who were at
the highest dose levels, displayed clinical response, compared with less
than 20 percent among those taking placebo. Researchers also observed a
trend toward improved histology, and a trend toward 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 extract and those who
did not, patients who presented with mild to moderate dysplasia 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," Dr. Papadimitrakopoulo was quoted as saying. "We cannot with
certainty claim prevention benefits from a trial this size."
Dong Shin, M.D., professor of hematology and medical oncology and Blomeyer
Endowed Chair in Cancer Research at Emory School of Medicine, agreed, but
indicated he thought this trial was 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 was quoted as saying. "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."
"The goal of this kind of research is to determine whether or not these
supplements have long-term prevention effects," Dr. Papadimitrakopoulou
said. "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."
SOURCE: Cancer Prevention Research, November, 2009
