Interphase cytogenetic (in situ hybridization) analysis of astrocytomas using archival, formalin-fixed, paraffin-embedded tissue and nonfluorescent light microscopy.

Astrocytomas contain nonrandom chromosomal abnormalities that recently have been correlated with shortened patient survival. Two frequently reported aberrations are trisomy 7 and monosomy 10. We assessed the numerical complement of chromosomes 7 and 10 in formalin-fixed, paraffin-embedded brain biopsy tissue from 28 diffuse astrocytomas by in situ hybridization using a nonfluorescent enzymatic detection system. Clinical follow-up of at least 5 years was available in 26 cases (93%). Monosomy 10 was identified in 7 cases (25%): astrocytoma, 1 case; anaplastic astrocytoma, 1 case; and glioblastoma, 5 cases. Trisomy 7 was identified in 11 cases (39%): astrocytoma, 5 cases; glioblastoma, 6 cases. Multivariate analysis revealed that monosomy 10 was the most statistically significant negative predictor of patient survival. Numerical chromosomal abnormalities are detectable in astrocytomas in archival tissue using interphase cytogenetics and nonfluorescent light microscopy. Although larger studies are required, our data suggest that potentially useful prognostic information may be obtained with this approach.