Abstract

Medulloblastoma is the most common malignant brain tumor during childhood. Currently, medulloblastoma is classified clinically according to age at presentation, metastatic status, and the presence of residual tumor following resection. Despite these clinical risk stratification and histological subtypes of medulloblastoma, all tumors give different responses to treatments and all have different prognosis. These findings suggest that medulloblastoma is a heterogeneous disease and clinical risk stratification and histological subtypes are not enough to predict outcome. Recent molecular and genetic studies indicate that medulloblastoma consists of different molecular subgroups and all of these subgroups have different prognosis. In the 2016 WHO brain tumor classification medulloblastomas were classified into four different subgroups according to molecular profiling. These molecular subgroups are WNT, Sonic Hedgehog (SHH), Group 3 and Group 4. WNT and SHH subgroups named according to the pathological pathways thought to be in their pathogenesis. In group 3 and 4 pathologic pathways are still unknown. Recent studies showed that these molecular subgroups have different demographics, clinical features and prognosis.

Ongoing researches will aim; 1) to reduce the treatment ( chemotherapy,radiotherapy) doses in good prognostic groups, and minimize the therapy related adverse effects. 2) to find new treatment approaches or target therapies especially in poor prognostic groups.

In this paper, we briefly reviewed the molecular subgroups of medulloblastoma, their clinical features and prognostic value.