Abstract

Purpose
To identify a specific subgroup of patients among elderly glioblastoma patients aged 70 years or older with unmethylated MGMT promoters (eGBM-unmethylated) who would significantly benefit from the addition of temozolomide (TMZ) to radiotherapy (RT).
Materials and Methods
Newly diagnosed patients with IDH wild-type eGBM-unmethylated treated with RT were included in this multicenter analysis (n=182). RT dose was 45 Gy in 15 fractions (62.3%), 60 Gy in 30 fractions, or 61.2 Gy in 34 fractions. For patients treated with RT plus TMZ (60.4%), TMZ was administered concurrently with RT, followed by six adjuvant cycles. The primary endpoint was overall survival.
Results
During a median follow-up of 11.3 months for survivors, the median survival was 12.2 months. The median survival duration significantly improved with the addition of TMZ to RT compared with that with RT alone (13.6 months vs. 10.5 months, p=0.028). In the multivariable analysis adjusted for clinical, radiological, and genetic biomarkers, the addition of TMZ significantly improved overall survival (hazard ratio, 0.459; p=0.006). In subgroup analysis, median survival was especially improved by 4–5 months in patients with residual disease (p<0.001), Karnofsky Performance Status ≥60 (p=0.033), and age ≤75 years (p=0.090). A significant benefit of TMZ was noted only in patients with two or three of the above factors (median survival, 14.1 months vs. 10.5 months, p=0.014).
Conclusion
The addition of TMZ significantly improved the survival of patients with eGBM-unmethylated treated with RT. The suggested criteria for the specific subgroup in these patients warrant external validation for clinical application.

• Keywords: Glioblastoma, MGMT, Aged, Temozolomide, Radiotherapy