- Estimated risk of seminal vesicle involvement is defined as PSA + ([Gleason score - 6] x 10) (i.e., if Gleason score ≤ 6, then PSA must be ≤ 30 ng/mL; if Gleason score = 7, then PSA must be < 20 ng/mL; if Gleason score = 8, then PSA must be < 10 ng/mL; if Gleason score = 9 or 10 patient is ineligible)