. . . with a caveat: While this article makes perfect sense, due to the known antioxidant properties of green tea (when prepared right!) there is the caveat of evolutionary pressures.
If you're not of Asian extraction, then probably your body has NOT evolved to take advantage of the precise properties of green tea as the Asian bloodlines will have evolved to.
That said, you will probably not suffer any ill effects from downing a cup or three of green tea a day. Also of course, green tea should not be the one and only prong in your plan of attack, you should also follow the other guidelines of The Body Friendly Zen Cookbook because the balanced approach and proper use of the foods will be far more beneficial than just trying one thing.
Last thing - this is not just for prostate cancer prone people - many cancers could be avoided by following a better diet, and the The Body Friendly Zen Cookbook has a lot of tips for keeping a healthy diet.