Gleason 7 or a rapidly rising PSA while not on hormone therapy are usually the danger signals that it's time to come off Active Surveillance. The problem with continued hormone therapy is that it may eventually force the cancer to become hormone resistant and impossible to contain. The other problems are the bad effects on his health - loss of bone density and muscle mass, hot flashes, cardiovascular effects, breast tenderness and enlargement, loss of sexual desire, and mood changes. But I'm sure his doctor has already told him all this. Both HDR brachy monotherapy and SBRT have very good rates of retaining erectile function (about 80% - especially when erectile function is good to begin with) while curing the cancer. It's something you may want to look into.