| Grade Group | Gleason score (sum) | Details / examples |
|---|---|---|
| Grade Group 1 | Gleason ≤6 (3+3) | Low grade; patterns only 3 (no pattern 4 or 5) |
| Grade Group 2 | Gleason 3+4=7 | Predominant pattern 3 with some pattern 4 |
| Grade Group 3 | Gleason 4+3=7 | Predominant pattern 4 with lesser pattern 3; worse prognosis than GG2 |
| Grade Group 4 | Gleason 8 (4+4, 3+5, 5+3) | High grade; includes 4+4 and combinations with pattern 5 present |
| Grade Group 5 | Gleason 9–10 (4+5, 5+4, 5+5) | Highest grade; pattern 5 predominant or combined high-grade patterns |