RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Drugs used in chemotherapy, such as temozolomide, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving radiation therapy together with temozolomide may kill more tumor cells. It is not yet known whether radiation therapy and temozolomide are more effective than radiation therapy alone in treating glioblastoma multiforme.

PURPOSE: This randomized phase III trial is studying radiation therapy and temozolomide to see how well they work compared with radiation therapy alone in treating patients with newly diagnosed glioblastoma multiforme.

OBJECTIVES:

Primary

• Compare overall survival rates in older patients with newly diagnosed glioblastoma multiforme treated with short-course radiotherapy with or without temozolomide.

Secondary

• Compare progression-free survival of patients treated with these regimens.
• Compare the nature, severity, and frequency of adverse events in patients treated with these regimens.
• Compare the quality of life of patient treated with these regimens.
• Determine the methylation status of the O6-methylguanine-DNA methyltransferase promoter.

OUTLINE: This is a multicenter, randomized study. Patients are stratified according to center, age (65-70 years vs 71-75 years vs ≥ 76 years), ECOG performance status (0-1 vs 2), and extent of resection at surgery (biopsy only vs complete or incomplete resection). Patients are randomized to 1 of 2 treatment arms.

• Arm I: Patients undergo radiotherapy once daily on days 1-5, 8-12, and 15-19 in the absence of disease progression or unacceptable toxicity.
• Arm II: Patients undergo radiotherapy as in arm I and receive oral temozolomide once daily on days 1-25.

Beginning 4 weeks after completion of radiotherapy and temozolomide, patients receive adjuvant oral temozolomide once daily on days 1-5. Treatment with temozolomide alone repeats every 28 days for up to 12 months in the absence of disease progression or unacceptable toxicity.

Patients complete quality of life questionnaires at baseline and periodically during study treatment.

Tissue samples are collected at baseline and analyzed for methylation status of the O6-methylguanine-DNA methyltransferase promoter.

After completion of study treatment, patients are followed every 3 months.

DISEASE CHARACTERISTICS:

• Histopathologically confirmed glioblastoma multiforme

  • Grade IV disease by WHO classification
  • Newly diagnosed disease

• Initial diagnostic surgery or biopsy performed within the past 4 weeks

• Not a candidate for standard radiotherapy (60Gy/30 fractions over 6 weeks) in combination with temozolomide

PATIENT CHARACTERISTICS:

• ECOG performance status 0-2
• Absolute granulocyte count ≥ 1,500/mm³
• Platelet count ≥ 100,000/mm³
• Creatinine ≤ 1.5 times upper limit of normal (ULN)
• Bilirubin ≤ 1.5 times ULN
• ALT and AST < 2.5 times ULN
• No known hypersensitivity to temozolomide or compounds with similar chemical composition to temozolomide
• No history of other malignancies except adequately treated nonmelanoma skin cancer, curatively treated in situ cancer of the cervix, or other curatively treated solid tumors with no evidence of disease for at least 5 years
• No serious active infection (e.g., wound infection requiring parenteral antibiotics) or other serious underlying medical conditions that would preclude study treatment
• No other condition (e.g., psychological or geographical) that would preclude study compliance

PRIOR CONCURRENT THERAPY:

• No prior chemotherapy
• No prior radiotherapy
• No prior or concurrent investigational therapy
• No concurrent surgical procedures for tumor debulking
• No concurrent stereotactic boost radiotherapy
• No other concurrent chemotherapy, immunotherapy, or biological therapy
• No concurrent epoetin alfa
• Concurrent corticosteroids allowed provided the patient has been on a stable or decreasing dose for at least 14 days