Molecular Classification of Medullobastomas by Whole Genome Expression Profiling.

Area of Science:

• Pediatric oncology
• Molecular diagnostics
• Central nervous system tumors

Background:

• Medulloblastoma (MB) is the most common pediatric central nervous system malignancy.
• MB is a high-risk tumor with metastatic potential.
• Molecular subtyping (WNT-activated, SHH-activated, group 3, and 4) refines diagnosis and prognosis.

Purpose of the Study:

• To classify pediatric medulloblastoma (MB) patients into four basic molecular groups.
• To compare these classifications with published data.
• To establish molecular classification for improved understanding and therapeutic planning.

Main Methods:

• Analysis of gene expression profiles using Affymetrix GeneChip Human Gene 1.0 ST Array.
• Utilized RNA extracted from fresh frozen tumor tissue.
• Employed molecular classification methodology established by P. Northcott (2011).

Main Results:

• 21 MB patients (median age 6 years; 14 boys, 7 girls) were analyzed.
• Group 4 was the most frequent subgroup (43%), followed by Group 3 (24%), SHH-activated (19%), and WNT-activated (14%).
• Molecular subgroup classifications correlated successfully with histopathological and molecular-genetic findings.

Conclusions:

• Established molecular classification of medulloblastomas (MBs) at the institution.
• Enhanced understanding of this heterogeneous disease.
• Aids clinicians in therapeutic planning for pediatric MB patients.