Single-arm phase ii study of conformal radiation therapy and temozolomide plus fractionated stereotactic conformal boost in high-grade gliomas: Final report

Purpose: To assess survival, local control and toxicity using fractionated stereotactic conformal radiotherapy (FSCRT) boost and temozolomide in high-grade gliomas (HGGs). Patients and Methods: Patients affected by HGG, with a CTV ₁(clinical target volume, representing tumor bed ± residual tumor + a margin of 5 mm) ≤ 8 cm were enrolled into this phase II study. Radiotherapy (RT, total dose 6,940 cGy) was administered using a combination of two different techniques: three-dimensional conformal radiotherapy (3D-CRT, to achieve a dose of 5,040 or 5,940 cGy) and FSCRT boost (19 or 10 Gy) tailored by CTV₁diameter (≤ 6 cm and > 6 cm, respectively). Temozolomide (75 mg/m²) was administered during the first 2 or 4 weeks of RT. After the end of RT, temozolomide (150-200 mg/m²) was administered for at least six cycles. The sample size of 41 patients was assessed by the single proportion-powered analysis. Results: 41 patients (36 with glioblastoma multiforme [GBM] and five with anaplastic astrocytoma [AA]) were enrolled; RTOG neurological toxicities G1-2 and G3 were 12% and 3%, respectively. Two cases of radionecrosis were observed. At a median follow-up of 44 months (range 6-56 months), global and GBM median overall survival (OS) were 30 and 28 months. The 2-year survival rate was significantly better compared to the standard treatment (63% vs. 26.5%; p <0.00001). Median progression-free survival (PFS) was 11 months, in GBM patients 10 months. Conclusion: FSCRT boost plus temozolomide is well tolerated and seems to increase survival compared to the standard treatment in patients with HGG.