I'm not an expert on this subject, all I know is that 7 years ago I was diagnosed with prostate cancer which was contained in my prostate. To me the only option is to get it out of your body which I did and have no regrets.
A friend who's cancer had spread outside of their prostate spent a long time having treatment and possibly will for the rest of their life.
Another friend was diagnosed 10 - 15 years ago who did not have his prostate removed, he had to take drugs which in the end were too much for his body to handle and died last year albeit at the age of 85.