I was also diagnosed with Gleason 3+4. MRI showed tumor contained within prostate gland. Post operative biopsy told a different story as the PC had grown through outside of the prostate ( extraprostatic extension) on the microscopic level. Doctor said 70% chance of recurrence. Remember the original biopsy only takes a few samples and it's not uncommon for Gleason scored to be raised after surgical biopsy. ( they could also be lower) As far as longevity, there's no Crystal ball with PC. Even if one lives many years before dying from PC, I can only imagine the last few years would not be pleasant. I personally would not ignore your Gleason 4. I wish you well.