Oral Cancer Protection Seen in Green Tea Extracts
Lee Swanson Research Update
Extracts from green tea may prevent the formation of mouth cancers in people with risk signs of the disease, according to a new study.
Over 50% of participants in the University of Texas M.D. Anderson Cancer Center study experienced a clinical response to the green tea extracts, according to findings published in Cancer Prevention Research.
"While still very early, and not definitive proof that green tea is an effective preventive agent, these results certainly encourage more study for patients at highest risk for oral cancer," lead researcher Vassiliki Papadimitrakopoulou, M.D.
"The extract's lack of toxicity is attractive—in prevention trials, it's very important to remember that these are otherwise healthy individuals and we need to ensure that agents studied produce no harm," he added.
Green tea contains between 30% and 40% water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3% and 10%. Oolong tea is semi-fermented tea and is somewhere between green and black tea. The four primary polyphenols found in fresh tea leaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC).
The study, a phase-II dose-finding trial, followed 41 people with oral leukoplakia, a condition that's a sign of oral cancer risk. The participants were assigned to receive either placebo or green tea extract at one of three doses, including 500 mg per meter squared of body mass (mg/m2), 750 mg/m2, or 1,000 mg/m2 three times a day.
The researchers collected oral tissue biopsies, which they say was "essential in that it allowed us to learn that not only did the green tea extract appear to have benefit for some patients, but we pointed to anti-angiogenic effects as a potential mechanism of action," explained co-researcher Anne Tsao, M.D.
Almost 60% of people taking the two highest doses of the green tea extracts had a clinical response. Just over 36% of people in the lowest extract dose group had a clinical response, compared to 18% in the placebo group, the researchers said.
Cancer Prevention Research 2(11):919-921, 2009