Concomitant chemoradiation (Ch-RT) in elderly newly diagnosed glioblastoma (GB) patients. Updated clinical outcome and molecular characteristics from the GLIOCAT study

Background

GB incidence is growing in elderly patients (pts), and approximately 50% of GB pts are over 65 years old. There is no standard treatment for newly diagnosed GB elderly patients. Elderly population is lacking of known molecular prognostic factors.

Methods

We report a multicenter study of newly diagnosed GB treated with Ch-RT(Stupp regimen). In this substudy we analysed outcome and prognostic factors in > 65y. Baseline characteristics and preliminary survival results will be presented at 2016 ASCO meeting, abstract 2045. We report the final survival and new data regarding pseudoprogression and molecular analysis.

Results

Between 2005 to 2014, 148 pts over 65y were enrolled. There were 117 (79%) >65-75y and 31 (21%) >75y with a median age of 72y. 19 pts (14.7%)presented pseudoprogression(psPD) in >65y, comparing to 42 (17.6%) in younger population (p = 0.47). MGMT methylation status was studied in 116 pts of which 65 (56%) were methylated vs 87 (40.3%) in ≤65y (p = 0.006). IDH1 status was studied in 82 pts >65y, none of them presented mutated IDH1vs 10 (5.6%) in younger pts(p = 0.029). Median follow up was 13.5 months (mo). In the global population median progression-free survival (mPFS) and overall survival (mOS) were 8 mo(95% CI, 7.49-8.5) and 14 mo (95% CI, 12.74-15.25) respectively, compared to 7 mo(95% CI, 6.09-7.9) and 10 mo (95% CI, 7.97-12.02) in >65y (p = 0.020 and p< 0.000). mOS in elderly pts presenting pseudoprogression was 16mo (95% CI, 13.23-18.76) vs 9 mo (95% CI 7.29-10.7) without it (p = 0.022). Pts with methylated MGMT had a higher incidende of psPD (p = 0.05). For elderly pts on multivariate analysis, gross total resection and pseudprogression but not KPS or MGMT were independent predictors of OS and PFS.

Conclusions

We confirmed that PFS and OS were poorer in >65y. There were no differences in the rates of pseudoprogression and MGMT methylation in the elderly population comparing to younger pts. Pseudoprogression had significant impact in OS. None of the elderly pts studied presented IDH1 mutation. For elderly patients, type of resection and pseudoprogression were the more relevant prognostic factors in newly diagnosed GB treated with the Stupp regimen.

Clinical trial identification

This work has been supported by the Marato Project: 665/C/2013

Legal entity responsible for the study

IGTP, IDIBELL, Fundacio Parc Salut Mar

Funding

Marato Project: 665/C/2013

Disclosure

All authors have declared no conflicts of interest.