A Prospective Study of Intensity-modulated Radiation Therapy Using a Standard Radiation Dose for High-grade Glioma

We evaluated the treatment outcomes of intensity-modulated radiation therapy (IMRT) using a standard radiation dose in patients with high-grade glioma (HGG).

We conducted a prospective, single-institutional, single-arm trial. Patients aged 20-75 years with histologically proven HGG were enrolled. Surgical procedures and chemotherapy regimens were not regulated. The prescribed dose of postoperative IMRT was 60 Gy in 30 fractions over six weeks. The primary endpoint was overall survival (OS). Secondary endpoints were progression-free survival (PFS), completion rate of IMRT, and Grade 3 or higher non-hematological toxicity.

Between 2016 and 2019, 20 patients were enrolled. According to the World Health Organization 2016 Classification, glioblastoma, anaplastic astrocytoma, and anaplastic oligodendroglioma were present in nine, six, and five of the recruited patients, respectively. Gross total resection, partial resection, and biopsy were performed in four, nine, and seven patients, respectively. All patients received concurrent and adjuvant chemotherapy using temozolomide with or without bevacizumab. The completion rate of IMRT was 100%. The median follow-up period was 29 months (range=6-68 months). Median OS and PFS were 30 and 14 months, respectively. No patients experienced Grade 3 or higher non-hematological toxicity. The 2-year OS rates were 100%, 57%, and 33% in Radiation Therapy Oncology Group-Recursive Partitioning Analysis (RTOG-RPA) classes I/II, IV, and V, respectively (p=0.002; log-rank test).

IMRT using the standard radiation dose in patients with HGG can be carried out safely. RTOG-RPA class appears to be useful to estimate patient prognoses.