In the Phase II dose-finding study, 41 oral leukoplakia patients were randomized between August 2002 and March 2008 to receive either green tea extract or placebo. Participants took the extract, an oral agent, for three months at one of three doses—500 per meter squared of body mass (mg/m2), 750 mg/m2, or 1,000 mg/m2—three times daily. To best assess biomarkers, participants also underwent a baseline and 12-week biopsy, an important component in the design of the study, the researchers said.
Of those taking green tea at the two highest doses, 58.8% had a clinical response, compared with 36.4% in the lowest extract dose and 18.2% in the placebo arm. At an extended follow-up with a mean of 27.5 months, 15 participants had developed oral cancer, with a median time to disease development of 46.4 months. Although not statistically significant, the green tea extract also improved histology and trended towards an improvement in a number of biomarkers that may play a vital role in predicting cancer development. According to the researchers, another important finding was that that the extract was well tolerated. Side effects, including insomnia and nervousness, were mostly seen in the high-dose group but produced no significant toxicity.
“While these are encouraging findings, much more research must be done before we can conclude that green tea may prevent oral or any other type of cancer,” said study author Vassiliki Papadimitrakopoulou, Professor in the Department of Thoracic/Head and Neck Medical Oncology, University of Texas M. D. Anderson Cancer Center. “It’s also important to remind people that this trial enrolled very few participants who, at the highest dose levels took the equivalent of eight cups of green tea three times a day. We need to further understand if green tea offers longer-term prevention effects for patients.”
A study published in Cancer Prevention Research shows that green tea extract may act as a cancer prevention agent for oral cancer in patients with a pre-malignant condition known as oral leukoplakia. The study is the first to examine green tea as a chemopreventative agent in this high-risk patient population. The researchers found that more than half of the oral leukoplakia patients who took the extract had a clinical response.