Hypofractionated intensity-modulated radiotherapy for primary glioblastoma multiforme

Area of Science:

• Radiation Oncology
• Neuro-oncology
• Medical Physics

Background:

• Glioblastoma multiforme (GBM) is an aggressive brain tumor with poor prognosis.
• Adjuvant radiotherapy is a standard treatment for GBM.
• Hypofractionation and intensity-modulated radiotherapy (IMRT) offer potential radiobiologic and conformal advantages.

Purpose of the Study:

• To assess the safety and efficacy of a novel hypofractionated IMRT regimen for adjuvant GBM treatment.
• To evaluate acute and chronic toxicity, treatment response, overall survival, and time to disease progression.

Main Methods:

• Pilot study involving 20 eligible patients with primary GBM.
• Intensity-modulated radiotherapy (IMRT) delivered 50 Gy in 5-Gy fractions over 2 weeks to the primary tumor/cavity.
• Simultaneously, 30 Gy in 3-Gy fractions was delivered to surrounding edema; toxicity graded using RTOG scores.

Main Results:

• Median time to disease progression was 6 months; median overall survival was 7 months.
• Minimal acute toxicity (Grade 0-1); however, 3 patients experienced Grade 4 late toxicity (brain necrosis) requiring surgery.
• Patients with brain necrosis had longer survival times (9-23 months); mortality was due to tumor recurrence, not necrosis.

Conclusions:

• Hypofractionated IMRT did not improve progression-free or overall survival compared to conventional fractionation for GBM.
• The 2-week treatment duration may offer palliative benefits.
• Further research is needed to optimize fraction size for highly conformal adjuvant RT in GBM.