Green tea may suppress prostate cancer in high-risk men

Chemicals in green tea may help inhibit development of prostate cancer in men at high risk, according to results of a randomized, controlled trial. 

Read: Upfront chemo called ‘standard’ in hormone-naïve PCa

The trial, which was funded by the National Institutes of Health/National Cancer Institute, was presented at the American Society of Clinical Oncology annual meeting in Chicago and also published online in Cancer Prevention Research (April 14, 2015).

Researchers from Moffitt Cancer Center, Tampa, FL, evaluated the effects of a year of treatment with catechins, substances in green tea that have interfered with the growth and functioning of cancer cells and promoted cell death in laboratory studies and prevented and decreased tumor growth in animals.

They studied 97 men with high-grade prostatic intraepithelial neoplasia (HGPIN) and/or atypical small acinar proliferation (ASAP), who were randomized to receive Polyphenon E (49 men), 200 mg twice a day, or placebo (48 men) for a year. Polyphenon E is a proprietary, standardized green tea extract containing a mixture of catechins, primarily the most potent catechin, epigallocatecin-3-gallate (EGCG).

NEXT: ASAP rate in treatment group 0/26

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Although the trial found no statistically significant overall difference in the number of cancer cases-5/49 men taking Polyphenon E, 9/48 with placebo-it did find that men with only HGPIN at the start of the study who received Polyphenon E ended up with a significantly lower combined rate of ASAP and cancer development (3/26) than the placebo group (10/25). More striking, the ASAP rate in the treatment group was 0/26, compared with 5/25 in the placebo group. ASAP comprises a group of prostate lesions in which the cells mimic cancer but aren’t changed enough to make a definitive diagnosis.

Moreover, PSA levels were significantly lower in men taking Polyphenon E, and EGCG levels were markedly higher. Adverse events didn’t differ between the treatment and placebo groups.

“We observed that green tea catechins reduced progression of prostate cancer and ASAP combined in men with an early precursor stage of prostate cancer,” said lead investigator Nagi B. Kumar, PhD, RD, of Moffitt Cancer Center. “These initial results are indeed provocative and need to be confirmed. Most of all, it may be important to test green tea administered over longer periods of time in a larger group of men who have the early precursor lesions called HGPIN.”

Marked differences in prostate cancer rates among different populations-Asian men, who drink a lot of green tea, have some of the lowest rates in the world-suggest an “environmental influence of the expression of disease and the possibility of preventing it using specific drugs,” Dr. Kumar noted. “However, to date there are no drugs that are safe to use to prevent prostate cancer in men with early symptoms of this disease, underscoring the need to identify novel prevention agents.”

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