Green tea supplement backed for prostate cancer reduction: RCT findings

31-May-2015 - Last updated on 01-Jun-2015 at 16:16 GMT

Consumption of a green tea extract has been suggested to reduce rates of cancer in certain indiviuals while reducing levels of the cancer biomarker prostate-specific antigen (PSA), say researchers.

Findings from the randomised, placebo controlled trial, suggest that daily consumption of a standardised, decaffeinated catechin mixture containing 400 mg epigallocatechin-3-gallate (EGCG) per day for one yearreduced combined rates of prostate cancer and atypical small acinar proliferation rates, as well as decreased levels of prostate-specific antigen in men who have premalignant prostate lesions or high-grade intraepithelial neoplasia.

The goal of the trial was to evaluate if a one-year intervention with green tea catechins (Polyphenon E ) could suppress prostate cancer development in men who had high-grade intraepithelial neoplasia (HGPIN) or atypical small acinar proliferation (ASAP).

Writing in Cancer Prevention Research, the research team reported findings from the trial – revealing that overall the difference in the number of prostate cancer cases at the end of one year between the two treatment groups was not statistically significant.

However, in men who only had HGPIN at the beginning of the trial, they observed a lower combined rate of ASAP and prostate cancer development with Polyophenon E (Poly E), said the team – led by Dr Nagi Kumar from Moffitt Cancer Center.

“This finding was driven by a decrease in ASAP diagnoses on the Poly E (0/26) compared to the placebo arm (5/25),” explained Kumar and colleagues, who added that a decrease in serum prostate specific antigen (PSA) was observed in people supplemented with the green tea product.

Study details

The researcher team compared Polyphenon E in 49 men to placebo tablets in 48 men over a one year treatment period, after pre-clinical, epidemiological and prior clinical trial data suggested that green tea catechins (GTCs) could reduce prostate cancer risk.

The 97 men all had high-grade prostatic intraepithelial neoplasia (HGPIN) and/or atypical small acinar proliferation (ASAP), and the primary study endpoint was a comparison of the cumulative one-year prostate cancer rates on the two study arms. Secondary measures included the cumulative rate of prostate cancer, blood PSA levels, and the rate of development of ASAP in men without ASAP but with HGPIN at baseline.

According to Kumar and colleagues, no significant differences were found in the number of total prostate cases were observed, with 5 cases in 49 participants for PolyE and 9 cases in 48 for placebo.

“A secondary endpoint comparing the cumulative rate of prostate cancer plus ASAP among men with HGPIN without ASAP at baseline, revealed a decrease in this composite endpoint: 3/26 (PolyE) versus 10/25 (placebo),” said the team.

Additionally, men receiving the green tea supplement had a significant decrease in prostate-specific antigen (PSA) levels – a biomarker that in combination with other risk factors is used to screen patients for prostate cancer, and high levels signify a higher risk of prostate cancer.

Source: Cancer Prevention Research
Published online ahead of print, doi: 10.1158/1940-6207.CAPR-14-0324
“Randomized, Placebo-Controlled Trial of Green Tea Catechins for Prostate Cancer Prevention”
Authors: Nagi B. Kumar, et al