LOS ANGELES: A new US study has shown that green tea may help reduce the risk of oral cancer, although scientists are reluctant to officially endorse green tea as an effective way of cancer prevention.

The study was published in the November issue of the Cancer Prevention Research, a journal of the American Association for Cancer Research.

Researchers at the University of Texas' Anderson Cancer Center assessed clinical response of green tea in oral pre-malignant lesions and found 58.8 percent of patients at the highest doses displayed clinical response, compared with 18.2 percent among those taking placebo.

They also observed a handful of biomarkers that may be important in predicting cancer development.

During the study, patients were followed for 27.5 months and atthe end of the study period, 15 of them developed oral cancers.

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Patients with mild to moderate dysplasia had a longer time to develop an oral cancer if they took green tea extract, but there was no difference in oral cancer development overall between those who took green tea and those who did not.

Although encouraged by the results, lead researcher Vassiliki Papadimitrakopoulo, a professor of medicine, cautioned against any recommendation that green tea could definitely prevent cancer.

"We cannot with certainty claim prevention benefits from a trial this size," said Papadimitrakopoulo. "More long-term research including studies in individuals at high risk is still needed to answer that sort of question."