2013 Background: Glioblastomas in elderly patients are associated with particularly poor outcome, with only few patients demonstrating long-term survival (LTS). Methods: To better characterize clinical and molecular correlates of LTS in elderly glioblastoma patients, we searched the German Glioma Network (GGN) database for patients aged 71 years or more with histological confirmation of glioblastoma and survival of at least two years after diagnosis. Results: Of 2071 glioblastoma patients enrolled in the GGN from 2004-2012, 425 patients were aged 71 years or more; of these, 27 patients (6.4%) survived for 2 years or more (median survival: 37.1 months, 95% confidence interval: 30.0-44.2 months). A comparison of these 27 patients with the 398 patients who survived shorter than 2 years (median survival: 6.2, 95% confidence interval: 5.2-7.2 months) revealed more intensive up-front treatment and a trend towards higher initial Karnofsky performance score as distinguishing clinical factors. Molecular analyses additionally showed more frequent O6-methylguanine-DNA methyltransferase ( MGMT) promoter methylation in the LTS patients. Isocitrate dehydrogenase (IDH) mutation was restricted to single patients and the frequency of telomerase reverse transcriptase ( TERT) promoter mutation did not differ between groups. Genome-wide DNA copy number and methylation profiling using 450k microarray analysis performed for 16 LTS patients and 40 control patients revealed limited differential DNA methylation and no specific copy number profiles linked to LTS. Conclusions: Collectively, our findings confirm that LTS is rare in elderly patients with glioblastoma and that clinical and tumor-associated molecular factors linked to LTS resemble those in standard age patients, except for less common IDH mutation.
PATH-18. MOLECULAR AND GENETIC ANALYSIS IDENTIFIES IDH MUTATION AS A KEY FACTOR OF LONG-TERM SURVIVAL IN GLIOBLASTOMA PATIENTS
