BFM classification of relapsed childhood ALL
| Group (% of relapsed cases) . | Definition of relapse . | % of patients reaching CR, % . | OS at 5 y with chemotherapy, % . | OS at 5 y with HSCT, % . |
|---|---|---|---|---|
| S1 (5%) | 1. Late extramedullary relapses | 99 | 60-70 | Not used |
| S2 (55%) | 1. Early extramedullary relapses | 97 | 40 | 60 |
| 2. Very early extramedullary relapses | ||||
| 3. Non-T late BM relapses | ||||
| 4. Non-T combined early/late relapses | ||||
| S3 (15%) | 1. Non-T early BM relapses | 80-85 | < 5 | 30 |
| S4 (25%) | 1. Very early BM relapses | 70-75 | < 5 | 25 |
| 2. Very early combined relapses | ||||
| 3. T-phenotype bone marrow relapses |
| Group (% of relapsed cases) . | Definition of relapse . | % of patients reaching CR, % . | OS at 5 y with chemotherapy, % . | OS at 5 y with HSCT, % . |
|---|---|---|---|---|
| S1 (5%) | 1. Late extramedullary relapses | 99 | 60-70 | Not used |
| S2 (55%) | 1. Early extramedullary relapses | 97 | 40 | 60 |
| 2. Very early extramedullary relapses | ||||
| 3. Non-T late BM relapses | ||||
| 4. Non-T combined early/late relapses | ||||
| S3 (15%) | 1. Non-T early BM relapses | 80-85 | < 5 | 30 |
| S4 (25%) | 1. Very early BM relapses | 70-75 | < 5 | 25 |
| 2. Very early combined relapses | ||||
| 3. T-phenotype bone marrow relapses |
Very early relapse indicates < 18 months from diagnosis; early relapse, > 18 months from diagnosis but < 6 months from treatment discontinuation; and late relapse, > 6 months from treatment discontinuation.