Author: Suvash Shrestha
Institution: Kathmandu Medical College, Nepal
A study was published in the November issue of Cancer Prevention Research describing the plausible positive effects of green tea. While green tea is well known to have beneficial effects in preventing heart disease and certain types of cancer, this study is one of the first to confirm the medicinal benefits of green tea.
As the main coordinator of this study, 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, assigned patients with high-risk oral premalignant lesions (OPL) to three experimental study groups and one control group at random. Green tea extract is supposed to suppress OPL by reducing stromal VEGF, which stimulates tumor growth. The study groups were given green tea in varying amounts of 500 mg/m2, 750 mg/m2, and 1000 mg/m2 of body surface area. The control group received a placebo drink that did not contain any true green tea leaves. After receiving the potion three times a day for 12 weeks, clinical and laboratory tests were performed.
While the difference was not statistically significant, the clinical response improved in a dose-dependent manner. 50% of the study group participants showed clinical benefits compared to only 18.2% in the placebo group. A histological examination of the OPL also showed that there was a significant improvement in the study group compared to the placebo group. Scientists used biomarkers such as VEGF, p53, Ki-67, Cyclin D1, and p16 to determine the status of the cancer. The changes in biomarkers were not as promising as the histological examinations. However, VEGF and Cyclin D1 were down-regulated in clinically responsive patients and up-regulated in clinically non-responsive patients.
Despite the positive results, Padadimitrakopoulo was cautious to make any conclusion. She said, "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. We cannot with certainty claim prevention benefits from a trial this size." However, there is no doubt that this study has further confirmed the potential benefits of green tea.
2. Tsao AS, Liu D, Martin J, Tang XM, Lee JJ, El-Naggar AK et al. Phase II Randomized, Placebo-Controlled Trial of Green Tea Extract in Patients with High-Risk Oral Premalignant Lesions. Cancer Prev Res (Phila Pa). 2009 Nov;2(11):919-21.