I have no experience but hope the information on this link will help.  www.cancerresearchuk.org/.../treatment

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

I am no Doctor but remember no option is perfect they all have their nuances, hormone therapy makes you emotional and crying even watching a movie. Surgery although they may say nerve sparring in a number of patents they have Erectile Dysfunction.

If you decide to go against the doctors best advise you best do your due diligence. When I say against the best advice I have read where some patients have gone abroad for Proton Beam Radiation for prostate cancer as UK only has 2 hospitals offering it and don’t want to offer it for Prostate Cancer although the United States they do it for Prostate Cancer.

The bottom line is that you want to live. You have to be happy with the decision that you make.