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This trial asked whether children with average-risk medulloblastoma could safely receive less radiation. Shrinking the boost to the tumour bed was safe; cutting the dose to the whole brain and spine in young children was not, so 23.4 Gy remains the floor for most.
Randomised phase 3 (Michalski et al., JCO 2021). 549 enrolled; 464 evaluable for the boost-volume comparison and 226 for the CSI-dose comparison. Five-year event-free survival was 82.5% with involved-field boost versus 80.5% with posterior fossa boost (HR 0.97; non-inferior), and 71.4% with 18 Gy CSI versus 82.9% with 23.4 Gy (HR 1.67; inferior). Post hoc molecular subgrouping showed the dose reduction harmed group 4 tumours most, while SHH tumours did better with involved-field boost. The trial set the current average-risk standard (23.4 Gy CSI plus tumour-bed boost to 54 Gy) and showed that further de-escalation must be subgroup-directed, which the successor trials (ACNS1422 for WNT, SIOP PNET5) now test.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
549 enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| 5-year event-free survival: boost volumeprimary | Involved-field boost | - | 82.5% | 0.97 | - | link |
| Posterior fossa boost | - | 80.5% | ||||
| 5-year event-free survival: CSI dose (age 3-7)primary | 18 Gy CSI | - | 71.4% | 1.67 | - | link |
| 23.4 Gy CSI | - | 82.9% |
Shares Medulloblastoma, Children's Oncology Group (COG), Vincristine, Proton therapy and the tags paediatric, cns.
Shares Medulloblastoma, Children's Oncology Group (COG), Vincristine, Proton therapy and the tags paediatric, cns.
Shares WNT-activated medulloblastoma, Lomustine (CCNU), Group 3 and group 4 medulloblastoma (non-WNT/non-SHH), Medulloblastoma and the tags paediatric, cns.
Shares Children's Oncology Group (COG), Proton therapy, Late effects and survivorship toxicity, Survivorship and late effects are neglected and the tags paediatric, cns.
Shares Paediatric oncology roadmap: cooperative-group cures → engineered immunity → drugs developed for children first, Vincristine and the tags paediatric, cns.
Shares Paediatric oncology roadmap: cooperative-group cures → engineered immunity → drugs developed for children first, Children's Oncology Group (COG), Vincristine, Proton therapy and the tags paediatric, cns.
Shares De-escalation, escalation and response-adapted therapy, Childhood Cancer Survivor Study (CCSS), Paediatric oncology roadmap: cooperative-group cures → engineered immunity → drugs developed for children first, Children's Oncology Group (COG) and the tag paediatric.
Shares Paediatric oncology roadmap: cooperative-group cures → engineered immunity → drugs developed for children first, Children's Oncology Group (COG), Late effects and survivorship toxicity, IMRT / IGRT (modern external beam) and the tags paediatric, cns.