I agree with the guys above who are basically telling you not to waste your money. I know of no AS program that would take a guy with a GS 4+3 - no matter what any genetic test said. You already have unfavorable risk prostate cancer - there's nothing further that Oncotype Dx or Prolaris can tell you.
...and would be unwilling to completely lose my sex life.
Who says you have to? When I was looking at potential treatments, that was my single biggest concern. The two therapies that preserved potency the best are HDR brachytherapy and SBRT, both at around 70-80% potency preservation. It is better in younger men, like yourself, and better if your potency is already still good. Daily low dose ED meds starting with your radiation treatments may up your odds still further.
At 6 years post SBRT, I have lost my ability to produce semen (some lucky guys don't even lose that), but I have not lost size or erectile function (also none of the sexual SEs sometimes associated with surgery - climacturia, Peyronie's, dysorgasmia, etc).
Allen - not an MD
•PSA=7.3, prostate volume=55cc, 8/17 cores G6 5-35% involvement
•SBRT 9 yr onc. results
•SBRT 7 yr QOL results
•treated 10/2010 at age 57 at UCLA,PSA now: 0.2,no lasting urinary, rectal or sexual SEsmy PC blog