534P - Glioblastoma treatment in patients older than 60 years: Hypofractionated radiotherapy and temozolomide versus conventional radiotherapy and temozolomide

Background

Treatment of glioblastoma patients under 70 years and with good Karnofski performance status (KPS>70) associates standard radiation therapy (SRT, 60 Gy in 30 fractions) with concomitant and adjuvant temozolomide for 6 monthly cycles (SRT-TMZ). Clinical trials of glioblastoma radiation treatment in patients older than 60 years (≥60-ys) showed no significant difference in survival comparing SRT to hypofractionated radiotherapy (HRT, 40.05 Gy in 15 fractions). Adding TMZ to HRT (HRT-TMZ) in patients ≥65-ys have translated into increased median overall survival (mOS) and progression-free survival (mPFS). In daily clinical practice, as in previous retrospective studies, older patients and/or those with KPS ≤70 may still be treated with radiation and temozolomide regardless of the MGMT tumor status, often opting for HRT-TMZ.

Methods

We retrospectively included all glioblastoma patients older than 60 years treated from 2017 to 2021 in our hospital with SRT-TMZ or HRT-TMZ. The primary endpoint was OS. The secondary endpoints were PFS, survival at 12 months (mo) and toxicity profile. Comparisons were made using Fisher´s exact test and Mann-Whitney test. Survival curves were estimated using the Kaplan-Meyer method and compared using the log-rank test.

Results

69 patients were treated, 33 with SRT-TMZ and 36 with HRT-TMZ. Median age was significantly different between these two groups (64 ys [range 60-70]) vs. 71 ys [range 62-85]), p<0.0001). KPS, extent of surgery, MGMT and IDH status did not show significant differences between groups. mPFS was 9 mo for SRT-TMZ vs. 10.2 mo for HRT-TMZ (p=0.57) and mOS was 14.8 mo vs. 13.8 mo (p=0.99), respectively. Treatment with SRT-TMZ was associated with increased thrombocytopenia events at the end of the first phase (p=0.01).

Conclusions

In real world, elderly glioblastoma patients pragmatically oriented to HRT-TMZ still had similar OS and PFS as younger patients treated with standard and potentially more toxic SRT-TMZ. This may support the extended use of HRT-TMZ in patients above 60 years.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.