Prospective study evaluating the radiosensitizing effect of reduced doses of temozolomide in the treatment of Egyptian patients with glioblastoma multiforme

May Gaber, Hanan Selim, Tamer El-Nahas

Department of Clinical Oncology, Cairo University, Cairo, Egypt

Purpose: In view of the documented toxicity of continuous daily radiosensitizer doses of temozolomide concomitant with radiation in the treatment of glioblastoma multiforme, we aimed to compare it with a different schedule of abbreviated radiosensitizer dosing.
Patients and methods: This was a randomized prospective study comparing toxicity and survival in 60 Egyptian patients with glioblastoma multiforme. Patients in arm I received temozolomide at a dose of 75 mg/m² daily with radiotherapy for 42 days, starting 4 weeks after surgery and reaching to a total radiation dose of 60 Gy/30 Fractions/6 weeks, while patients in arm II received temozolomide at a dose of 75 mg/m² concomitantly with the same radiotherapy schedule daily in the first and last weeks of the same radiotherapy program.
Results: Common grade 1–2 adverse events were malaise in 28 patients (46.7%), followed by alopecia (40%) and nausea (26.7%). Grade 3–4 convulsion and decreased level of consciousness was seen in only four patients who were all from arm I. The median progression-free survival (PFS) for the entire study population was 10.6 months (95% confidence interval [CI] 7.3–14), and PFS at 12 months was 32%. The median PFS in arm I was 8.8 months (95% CI 5.9–11.7) and in arm II 11.5 months (95% CI 8.9–14.2), and PFS at 12 months for both arms was 32% and 30% respectively (P=0.571). The median overall survival (OS) of the whole group of patients was 14.2 months (95% CI 13–15.5), and OS was 70% at 12 months and 25% at 18 months. The median OS for patients in arm I was 12.3 months (95% CI 7.7–16.9), whereas in arm II it was 14.3 months (95% CI 14–14.7) (P=0.83).
Conclusion: Reduced radiosensitizer dosing of temozolomide concomitant with radiotherapy in glioblastoma multiforme exhibited comparable efficacy with a classic continuous daily schedule, though with better tolerability.

Keywords: glioblastoma multiforme, temozolomide, radiosensitizer, high-grade glioma