Lupron is the most powerful drug I have ever taken. You will immediately feel the side-effects, the extent and intensity of which can vary from patient to patient. No fun for anyone. That said, it does immediately drop your testosterone, which is the food for your cancer cells. Probably good to start on this drug for 30-60 days prior to either radiation or surgical treatment. It also can shrink the tumor(s) on your prostate. Also, continuing on the lupron post-treatment is also advisable in my opinion for a short period time. Think of post treatment lupron as cleaning up any cancer cells that may be hiding in the corners of your prostate. Unlikely after treatment but better safe than sorry.