Health Spectator

There is evidence that the polyphenols found in green tea may slow the progression of prostate cancer, according to a study published recently in Cancer Prevention Research,¹ a journal of the American Association for Cancer Research (AACR).

According to researcher James A. Cardelli, PhD, professor and director of basic and translational research in the Feist-Weiller Cancer Center, LSU Health Sciences Center, Shreveport, LA, men with prostate cancer who consumed the active compounds in green tea demonstrated a significant reduction in serum markers predictive of prostate cancer progression.

“The investigational agent used in the trial—Polyphenon E—may have the potential to lower the incidence and slow the progression of prostate cancer,” Cardelli said.

Unfortunately, the Phase II trial of Polyphenon E from Polyphenon Pharma was not a randomized double-blind trial, which would have been more conclusivie in ruling out other factors such as lifestyle changes in effecting the positive cancer results witnessed in the participants.

A paper published in another AACR journal in December 2003² found that certain polyphenols from green and black tea were potent inhibitors of the Bcl-2 family of antiapoptotic proteins. Antiapoptotic proteins enable cancer cells to avoid normal cell death. The immortality of cancer cells makes them ultimately lethal to their hosts.

The biomarkers Cardelli’s team studied included hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and prostate specific antigen (PSA). HGF and VEGF are good prognostic indicators of metastatic disease. PSA is the marker most commonly used to diagnose prostate cancer.

The study included 26 men, aged 41 to 72 years, diagnosed with prostate cancer and scheduled for radical prostatectomy. Patients consumed four capsules of Polyphenon E until the day before surgery. According to Cardelli, the dosage was equivalent to about 12 cups of normally brewed green tea. The duration of the study for 25 of the 26 patients ranged from 12 days to 73 days, with a median time of 34.5 days.

Findings showed a significant reduction in serum levels of HGF, VEGF and PSA after treatment, with some patients demonstrating reductions in levels of greater than 30 percent, according to the researchers.

Alluding to the fact that the trials were not randomized, William G. Nelson, V., M.D., Ph.D., professor of oncology, urology and pharmacology at the Johns Hopkins Kimmel Cancer Center in Baltimore, MD, remarked, “this trial is provocative enough to consider a more substantial randomized trial.” Nelson is also a senior editor for Cancer Prevention Research.

The same researchers are collaborating in a study being performed at Columbia University (New York, NY) to study the effects of polyphenols on breast cancer patients.

“There is reasonably good evidence that many cancers are preventable, and our studies using plant-derived substances support the idea that plant compounds found in a healthy diet can play a role in preventing cancer development and progression,” Cardelli said.

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