title: Impact of morphology, MIB-1, p53 and MGMT on outcome in pilocytic astrocytomas.
abstract: Pilocytic astrocytoma (PA) is the most common glioma in the pediatric population. PAs can exhibit variable behavior that does not always correlate with location, yet at present there is no way to predict which tumors will be more aggressive. To address this problem, an institutional cohort of 147 PAs (118 with outcome data) from both cerebellar and noncerebellar locations (spine, diencephalon, midbrain, brainstem and cortex) was utilized. Parameters included quantification of characteristic morphologic variables as well as genes previously shown to be of relevance in high-grade gliomas, including MIB-1, p53 and MGMT. In this cohort, the classic biphasic appearance was most common in cerebellar tumors, whereas noncerebellar tumors were predominantly microcystic. Associations with outcome suggest that the presence of degenerative atypia may be a favorable factor in PAs. Oligodendroglial morphology and the absence of leptomeningeal invasion are adverse histologic factors, but only in cerebellar tumors. Conversely, MIB-1 proliferation index and p53 and MGMT expression do not correlate with outcome. Morphologic biomarkers thus do exist for PAs, but the utility of each biomarker varies according to location. These results suggest that PAs differ fundamentally according to location; therefore, biological behavior may not simply depend on extent of resection.
authors.affiliation: Department of Pathology, University of Kentucky, Lexington, KY, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Horbinski
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Hamilton
authors.forename: Colleen
authors.initials: C
authors.lastname: Lovell
authors.forename: Judith
authors.initials: J
authors.lastname: Burnham
authors.forename: Ian F
authors.initials: IF
authors.lastname: Pollack
mesh_terms: D000293:Adolescent; D001254:Astrocytoma / Q000378:metabolism* / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000032:analysis / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015254:DNA Modification Methylases / Q000502:physiology*; D045643:DNA Repair Enzymes / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D019394:Ki-67 Antigen / Q000502:physiology*; D008297:Male; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000502:physiology*
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes