All kidding aside, I asked my oncologist this same question. "How long will my ADT injections work?" Her response was right on the mark. "ADT injections work until they don't and when they don't we will try something else, again, and again, until we find something that works." What works best I asked? She replied "Quality of life, your quality of life tells me everything I need to know about our treatments success." I have taken great comfort in that of the years (last 2 years).