Background and purpose: In order to investigate the feasibility, toxicity and antitumor efficacy of hyperfractionated radiation therapy, 37 adult patients with incompletely resected supratentorial low-grade glioma were entered into a phase II study.
Materials and methods: The radiation therapy dose was 55 Gy in 50 fractions in 25 treatment days over 5 weeks to the tumor plus a 2-cm margin, with an additional 17.6 Gy given in 16 fractions in 8 treatment days over 1.5 weeks to the tumor plus a 1.5 cm margin, using 1. Gy b.i.d. fractionation with a 6 h interfraction interval. The total tumor dose was 72.6 Gy in 66 fractions in 33 treatment days over 6.5 weeks.
Results: The median survival time (MST) for all 37 patients has not yet been attained, while 5- and 7-year survival rates were 75% and 69%, respectively, The median time to tumor progression (MTP) has also not yet been attained, while 5- and 7-year progression-free survival (PFS) rates were both 70%. There was no difference in survival or PFS regarding histology, although patients with oligodendroglioma and mixed glioma had similar survival, both being higher than that of ordinary astrocytoma. On univariate analysis of potential prognostic factors, age, Karnofsky performance status (KPS), neurologic status and extent of surgery were found to influence survival. The toxicity of HFX RT was generally assessed as mild to moderate.
Conclusion: HFX RT is feasible with mild to moderate toxicity. Further studies are warranted with more patients and longer follow-up before testing it against standard fractionation RT in this patient population.