Hi Andy - You are young and seem to have been diagnosed by chance - although you probably don't think so at the moment this is a good thing - you have cancer but early diagnosis is by far the most important factor in cancer cure.
Judging by your Gleason score and biopsy result you have what would seem to be, at the moment, a contained relatively small area of cancer that is, as yet, not very aggressive. With surgery now, at your age and with your cancer spread, recovery should be quick and your chances of successful nerve sparing high. Your chances of full recovery of sexual function should be very good and your chances of full cancer cure around 96% or higher. With the surgery the only thing more or less guaranteed is that future orgasms will be dry (no seminal fluid) but this shouldn't really be a big concern as it shouldn’t effect your sexual function.
I chose radiotherapy but I was 59 - I assume you haven't been offered radiotherapy because of your age. Radiotherapy can, in a small number of cases, cause problems 15-20 years down the road and if you are 70 this shouldn't be a concern - you on the other hand will still only be 60 in 20 years.
You say Active Surveillance is an option but as I understand it this means checking PSA levels regularly and then having repeat MRI scans or biopsies if there are any sudden rises. PSA numbers and MRI scans are not an exact science - you can have a PSA of 5 and still have a more aggressive cancer than someone with a PSA of 20 - also MRI scans can show false clear results when cancer is present - as mine did. Biopsy is the only surefire way to check progression so active surveillance could mean regular biopsies which is not a pleasant thing.
These links are quite well informed and well written articles from last year and I have quoted an interesting paragraph below. (hopefully the site will allow me to include links in my post as I found these very helpful myself).
“If your doctor says you are a candidate for active surveillance, and you don’t have a family history of cancer and you are not of African descent, you may want to consider it, because it won’t affect your sex life or your urinary continence. However, it is not fun to get repeat biopsies, and if you are the kind of man who will constantly worry about having cancer – even if it seems unlikely to progress – this may not be for you.
If you are likely to choose surgery after a few years of active surveillance because you don’t want to live with the cancer and you want peace of mind, then please understand that your chances of recovery of potency are better sooner rather than later. Younger men who are potent before surgery do better.”
You have the luxury of things not being overly urgent at the moment - take your time and get the Toolkit from this site and remember that any statistical figures you read are skewed a bit towards people much older than you.
Be positive - Rather than get too depressed about having cancer try to balance your thoughts in terms of how lucky you are that you have been diagnosed very early and therefore your outlook at this stage for full cure and problem free recovery are extremely high.