Postoperative histologic grading
| Grade | Histologic Characteristics |
|---|---|
| 0 | No therapeutic effects observed |
| 1 | Degenerative changes in tumor cells but no destruction of tumor nests |
| 2 | Destruction and disappearance of tumor nests but viable cells remain |
| 2a | Viable cells occupy large areas (>1/3) |
| 2b | Viable cells occupy small areas (<1/3) |
| 3 | Tumor cells remain but appear nonviable |
| 4 | No tumor cells remain |