International Neuroblastoma Risk Group (INRG) consensus pretreatment classification schema [4]
| INRG Stage | Age (month) | Histologic category | Grade of tumor differentiation | MYCN | 11q Aberration | Ploidy | Pretreatment risk group | |
|---|---|---|---|---|---|---|---|---|
| L1/L2 | GN maturing; GNB intermixed | A | Very low | |||||
| L1 | Any, except GN maturing or GNB intermixed | NA | B | Very low | ||||
| Amp | K | High | ||||||
| L2 | <18 | Any, except GN maturing or GNB intermixed | NA | No | D | Low | ||
| Yes | G | Intermediate | ||||||
| ≥18 | GNB nodular; neuroblastoma | Differentiating | NA | No | E | Low | ||
| Yes | H | Intermediate | ||||||
| Poorly differentiated or undifferentiated | NA | |||||||
| Amp | N | High | ||||||
| M | <18 | NA | Hyperdiploid | F | Low | |||
| <12 | NA | Diploid | I | Intermediate | ||||
| 12 to <18 | NA | Diploid | J | Intermediate | ||||
| <18 | Amp | O | High | |||||
| ≥18 | P | High | ||||||
| MS | <18 | NA | No | C | Very low | |||
| Yes | Q | High | ||||||
| Amp | R | High | ||||||
Pretreatment risk group H has two entries. 12 months=365 days; 18 months=547 days; blank field=“any”; diploid (DNA index ≤1.0); hyperdiploid (DNA index >1.0 and includes near-triploid and near-tetraploid tumors); very low risk (5-year EFS >85%); low risk (5-year EFS >75% to ≤85%); intermediate risk (5-year EFS ≥50% to ≤75%); high risk (5-year EFS <50%). GN, ganglioneuroma; GNB, ganglioneuroblastoma; Amp, amplified; NA, not amplified; L1, localized tumor confined to one body compartment and with absence of image-defined risk factors (IDRFs); L2, locoregional tumor with presence of one or more IDRFs; M, distant metastatic disease (except stage MS); MS, metastatic disease confined to skin, liver and/or bone marrow in children <18 months of age; EFS, event-free survival. Note: This table is the same as Fig. 2 in Cohn SL et al. (2008) The International Neuroblastoma Risk Group (INRG) Classification System: An INRG Task Force Report