I’m not sure what they mean by at your age - unless they mean because you’re so young. 
Not my specialist subject but another option is to do nothing, just wait and see how things develop. Watchful waiting or active surveillance. This may seem counter-intuitive but it avoids the side effects of surgery and if the cancer is slow growing it can be less risky than surgery, radiotherapy or hormone therapy. 
Obviously if it isn’t slow growing the situation is different.

I’m not sure what they mean by at your age - unless they mean because you’re so young. 
Not my specialist subject but another option is to do nothing, just wait and see how things develop. Watchful waiting or active surveillance. This may seem counter-intuitive but it avoids the side effects of surgery and if the cancer is slow growing it can be less risky than surgery, radiotherapy or hormone therapy. 
Obviously if it isn’t slow growing the situation is different.

Sorry but I am no Doctor but be careful in taking bad advice. Careful watching is only for those with a particular Gleason score. When they say you are young it means you have strength to recover from the surgery, be clear of cancer and get back erections over time