Histological criteria for Wilms' tumour subtyping in SIOP WT 2001 trial
| Tumour type | CIC (%) | Histological features (% of a tumour) | ||
| Epithelium | Stroma | Blastema | ||
| Completely necrotic | 100 | 0 | 0 | 0 |
| Regressive | >66 | 0–33 | 0–33 | 0–33 |
| Mixed | <66 | 0–65 | 0–65 | 0–65 |
| Epithelial | <66 | 66–100 | 0–33 | 0–10 |
| Stromal | <66 | 0–33 | 66–100 | 0–10 |
| Blastemal | <66 | 0–33 | 0–33 | 66–100 |
CIC, chemotherapy-induced changes.