Radiation Therapy With or Without Temozolomide in Treating Patients With Low-Grade Glioma

RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. 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. It is not yet known whether radiation therapy is more effective when given together with or without temozolomide in treating patients with low-grade glioma.

PURPOSE: This randomized phase III trial is studying radiation therapy so see how well it works when given together with or without temozolomide in treating patients with low-grade glioma.

OBJECTIVES: Primary - To determine whether the addition of temozolomide to fractionated radiotherapy improves the progression-free survival (PFS) of patients with symptomatic or progressive low-grade gliomas. - To determine whether the addition of temozolomide to fractionated radiotherapy improves the median overall survival (OS) of these patients. Secondary - To determine whether combination therapy with temozolomide and radiotherapy improves or maintains cognition and quality of life compared to radiotherapy alone. - To compare the toxicities (severe or worse [≥ grade 3]) of radiotherapy with vs without temozolomide in these patients. - To assess the impact of the presence or absence of 1p and 19q deletion on PFS and OS. - To determine the impact of 1p and 19q status on PFS and OS of patients treated with temozolomide. - To create a tumor and tissue bank, including plasma and germ line DNA, within the ECOG Pathology Coordinating Office. OUTLINE: This is a multicenter study. Patients are stratified according to age (< 40 years vs ≥ 40 years), 1p and 19q status (both deleted vs either/both intact vs undeterminable), pre-operative maximum tumor diameter (< 6 cm vs ≥ 6 cm [based on T2 or FLAIR MRI]), Karnofsky performance status (60-70% vs 80-100%), and contrast enhancement on pre-treatment MRI scan (present vs absent). Patients are randomized to 1 of 2 treatment arms. - Arm I: Patients undergo 3-dimensional conformal or intensity-modulated radiotherapy once daily 5 days a week for 5½ weeks (28 fractions). - Arm II: Patients undergo radiotherapy as in arm I and receive concurrent oral temozolomide once daily for 5½ weeks. Beginning 28 days after completion of chemoradiotherapy, patients receive oral temozolomide alone once daily on days 1-5. Treatment with temozolomide repeats every 28 days for 12 courses in the absence of disease progression or unacceptable toxicity. Some patients undergo quality-of-life and neurocognitive (e.g., visual scanning speed, divided attention, language, memory, and fine motor skills) assessments at baseline, annually until disease progression, and at the time of disease progression. Tumor tissue samples are collected at baseline for confirmation of diagnosis and determination of 1p and 19q deletion status. Peripheral blood, serum, and additional tumor tissue samples may be collected for further research studies. After completion of study treatment, patients are followed up periodically for up to 15 years.