Comparative genomic hybridization analysis of radiation-associated and sporadic meningiomas

Ionizing irradiation to the skull is a known risk factor for meningioma development. To gain insight into the molecular mechanisms that underlie radiation-associated meningioma (RAM), we characterized the somatic genetic alterations in 16 RAMs by using comparative genomic hybridization and compared the pattern of alterations with 17 nonradiation-associated meningiomas (non-RAM). Most tumors (29/33;87.9%) displayed at least one DNA copy number alteration, and 11 out of 33 (33%) exhibited four or more changes. The mean number of DNA copy number changes was similar in RAMs (2.4±1.9) and in non-RAMs (2.5±1.9). The most common DNA losses were noted in chromosome 22 (56.2% in RAM, and 47% in non-RAM) and chromosome 1 (37.5% in RAM and 35.3% in non-RAM), with no significant differences between the two groups. Noteworthy, gain in DNA copy number of chromosomes 8 and 12 was detected in two RAM tumors only. In conclusion, no significant differences were noted between RAMs and non-RAMs regarding the number of genetic changes and the extent and frequency of chromosomes 1 and 22 losses. These preliminary data suggest that the tumorogenic pathways of meningioma formation are similar, regardless of previous skull irradiation.