Chromosome instability in malignant astrocytic tumors detected by fluorescence in situ hybridization.

Malignant tumors intrinsically manifest genetic instability, and consequently genetic aberrations successively accumulate in tumor cells as the tumor progresses. However, the relationship of genetic instability and biological behavior still remains to be investigated in malignant tumors. In the present investigation, the relationship between chromosomal instability and patient prognosis was studied in 19 malignant gliomas. Chromosomal instability was estimated by numerical variation in chromosomes 7, 10 and 17 which was measured by fluorescence in situ hybridization (FISH), and DNA ploidy was determined by laser scanning cytometry. The mean number of fractions was significantly higher in cases with DNA aneuploidy than in those with DNA diploidy. The tendency toward higher fractions in glioblastomas existed, although it did not reach statistical significance. Kaplan-Meier survival rate analysis demonstrated significantly lower survival rates in patients with higher fractions of chromosome 7 (>5) than others. Our results suggest that DNA aneuploidy in malignant gliomas reflects an underlying chromosomal instability, and that this instability is associated with clinical behavior.