There is nothing magic in green tea neither! Its components are thought to have protective effects against Prostate cancer.
Green tea is rich in polyphenols of catechin's type.
Specifically, Epigallocatechin gallate (EGCG) is a type of catechin that acts as androgen antagonist.
Thus, it stops further prostate cancer proliferation, preventing advancement or metastasis.
It can be easily tolerated, with gastro-intestinal problems being as most common side effects.
You can enjoy green tea on daily basis, but do not overpass one cup per day. If you consume prostate-beneficial herbs/foods on daily basis, altogether, they can help preventing cancer and/or other problems onset.
https://www.flickr.com/photos/vordichtung/5869946403" title="green tea by Martin Phox, on Flickr