[Molecular Classification and Treatment of Medulloblastoma: An Update]

Medulloblastoma is a prevalent malignant pediatric central nervous system tumor. While medulloblastoma was historically risk-stratified by clinical factors, the WHO 2021 classification integrated molecular profiling, fundamentally transforming its diagnosis and management. The tumor is categorized into four primary molecular subgroups using techniques such as DNA methylation profiling: WNT-activated, SHH-activated, and non-WNT/non-SHH (Groups 3 and 4). WNT-activated tumors generally exhibit the most favorable prognosis. SHH-activated tumors present varying outcomes depending on patient age and genetic alterations, such as TP53 mutations. Group 3 tumors, especially those with MYC amplification, frequently metastasize and have poor outcomes, whereas Group 4 tumors show a more prolonged clinical course. Standard treatment involves maximal safe resection, craniospinal irradiation (CSI), and chemotherapy. However, to mitigate severe late complications, molecular subtyping now enables precision and risk-adapted therapies. This includes exploring CSI dose reduction for the favorable WNT subgroup and utilizing novel molecular biomarkers for Groups 3 and 4. For infants, treatment primarily relies on chemotherapy to avoid CSI. Furthermore, recurrence patterns strongly correlate with these molecular subtypes. Re-biopsy and molecular re-evaluation are crucial upon relapse to distinguish genuine recurrences from radiation-induced secondary tumors.