There are a few positive RCTs. Nothing earth-shattering and, by itself, green tea and EGCG likely will not change your prognosis much. But my opinion is that it is good to move the needle in the right direction (of course weigh the cost and the side effects). Green tea is cheap. I get organic green and white teas and drink tea throughout the day (white is possibly superior to green but most studies I've seen are centered on green).
I have also seen a null RCT but this is an example of one of the weak positive RCTs (I have yet to see evidence that green tea and/or EGCG is a negative for prostate cancer and if someone knows of a negative, please tell me):