Welcome to the forum, Fed, glad you found us.
Stage 3 would mean that the cancer had escaped the prostate capsule. Possilbe they saw something on the MRI that indicated that. But the MRI is not 100% definitive. although its usually pretty good. Might have been a close call and they called it that way.
It is fairly common for a gleason score to be upgraded after surgery. Happens about
30-40% of the time. Less often, but sometimes, the gleason score is downgraded. So you were one of the "lucky"ones. (3+4) is low intermediate risk. Did you have negative margins? From what you say in your post, it looks like there is a good chance you've been cured.
Dx Age 64 Nov 2014, 4.3
BX 3 of 12 cores positive original pathologyG6, G6, G8 (3+5)
downgraded to 3+3=6 by Dr Epstein, JH
RALP with Dr Ash Tewari Jan 6, 2015
Post surgical pathology – G7 (3+4), ECE, Margins, LN, SV all negative
PSA @ 6 weeks 2/15, .<02, 4/15 <.02 7/15 <.02, 10/15 0.00 (new lab) , 1/16, 0.00
My Story: tinyurl.com/oo9x4aq