Repeated molecular testing in gliomas: a retrospective study of 53 cases.

The value of repeated molecular testing in patients with multiple resections of gliomas is unclear. The purpose of this study was to assess for evidence of molecular changes for chromosome 1p/19q deletions and epidermal growth factor receptor (EGFR) amplification by fluorescence in situ hybridization in 53 glioma cases in which repeated testing was done. Paired results for 1p evaluation demonstrated a change in the profile from intact to loss in 1 (2%) of 50 cases; 19q evaluation demonstrated a change in profile in 4 (10%) of 41 cases. There was no change in the EGFR expression in any of the cases tested. There was no change in the clinical management based on the repeated molecular tests in patients with discrepant repeated results. Hence, there seems to be no indication for reflex repeated 1p/19q or EGFR testing in gliomas at the time of repeated biopsy or resection.