Recently, there has been an emphasis on prostate cancer chemoprevention: agents that prevent the progression of prostate cancer. A team of scientists led by Nagi B. Kumar from the Moffitt Cancer Center have recently published the outcomes of a randomized clinical trial that evaluated the effectiveness and safety of the active components existent in green tea that can prevent prostate cancer in men who have pre-malignant injuries. The results were presented during the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting, Chicago.
About 20% of green tea is consumed in Asian countries where prostate cancer death rates are one of the lowest in the world. The risk to develop such malignancy seems to increase among Asian men that leave their original dietary habits after migrating to the United States.
Laboratory studies have evidenced that substances in green tea known as “catechins” can inhibit the growth, motility and invasion capacity of cancer cells and stimulate their death. Catechins, of which epigallocatechin-3-gallate (EGCG) is the most powerful and abundant found in green tea, can prevent and reduce the growth of tumors in animal models.
This study evaluated if a 1-year intervention with catechins and green tea could suppress prostate cancer progression in male individuals who had high-grade intraepithelial neoplasia (HGPIN) or atypical small acinar proliferation (ASAP). The investigators used decaffeinated green tea capsules named Polyphenon E with a mix of catechins (mostly EGCG) at a dose of 200 mgs twice daily.
Polyphenon E given to 49 men and placebo tablets given to 48 men were compared during a year of treatment, with results not showing a statistically significant difference in cancer development. However, researchers observed that in those patients who only had HGPIN during the initial phase of the trial there was a lower combined rate of ASAP (group of lesions that can be diagnosed as prostate cancer) and prostate cancer advancement with Polyophenon E. Further, men on Polyphenon E had significant lower levels of prostate-specific antigen (PSA) – a biomarker used to screen patients for prostate cancer.
Importantly researchers noticed a significant increase of EGCG levels in the blood plasma of men on Polyphenon E, and the capsules were well tolerated in this group of men.