Assessment of tumor cell invasion factors in gliomatosis cerebri

Genetic aberrations in gliomatosis cerebri

OBJECTIVE

Identifying the genetic alterations in gliomatosis cerebri (GC) may yield clinically useful prognostic markers and provide clues as to whether GC represents a distinct pathological entity or is an extreme form of diffusely infiltrative glioma.

METHODS

Clinical histories, treatment histories, magnetic resonance imaging, and pathological analysis of patients with GC treated at either the University of California San Francisco or the Mayo Clinic were reviewed. Degenerate oligonucleotide-primed polymerase chain reaction was performed on biopsy samples of GC. Comparative genomic hybridization was used to determine relative deoxyribonucleic acid copy number. We evaluated relationships of clinical and radiological treatment and comparative genomic hybridization data to survival after diagnosis with Cox regression analysis.

RESULTS

Radiographic analysis and biopsy specimens were available for study in 29 patients (17 men, 12 women). Comparative genomic hybridization was successfully performed in 22 patients. Contrast enhancement was the most significant predictor of poor survival (P = 0.0026). Loss of chromosomes 13q and 10q and gains of 7q were also independent significant predictors of poor survival (P = 0.0032, 0.0335, and 0.0487, respectively). Patients treated with temozolomide or with radiation therapy had improved survival, but this effect did not reach statistical significance (P = 0.180 and 0.124, respectively).

CONCLUSION

Chromosomal aberrations associated with aggressive astrocytomas are predictors of poor outcome in patients with GC. This suggests that GC may be an architectural variant of diffuse astrocytomas. The presence of these aberrations and the presence of any contrast enhancement on magnetic resonance imaging scans are possible stratifiers for patients with GC. Stratification of GC into higher- and lower-grade forms may be useful in tailoring treatments to patients with this disease.

Molecular genetic alterations in gliomatosis cerebri: what can we learn about the origin and course of the disease?

Gliomatosis cerebri (GC) is a neuroepithelial neoplasm with extensive infiltration of large parts of the brain. Recent data showing the involvement of TP53 mutation or nuclear protein accumulation in some cases have linked the astrocytic phenotype of the tumor cells to TP53 alterations frequently found in common astrocytomas. However, the frequency of these alterations is low, and other molecular genetic changes have been only rarely identified. Those found in common high-grade astrocytomas and glioblastomas are usually missing in GC. The distribution of TP53 point mutations, as well as non-coding polymorphic markers and some cytogenetic data, support a monoclonal origin in some cases, and are at least compatible with it in most cases, while no conclusive data suggesting a polyclonal origin have been reported. This raises the question of mechanisms responsible for the enhanced infiltrative potential of the tumor cells in this disease, which have not yet been identified.