Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed* supratentorial low-grade glioma, including 1 of the
following:

- Grade 2 astrocytoma

- Grade 2 oligodendroglioma

- Grade 2 oligoastrocytoma (mixed glioma containing astrocytoma and
oligodendroglioma)

- NOTE: *If the pathology from multiple procedures supports the diagnosis of a brain
tumor, the qualifying pathology of grade 2 astrocytoma, oligodendroglioma, or
oligoastrocytoma must be the most recent pathological diagnosis; no pathological
diagnosis of grade 3 or 4 glioma at any time

- Paraffin-embedded tumor specimen available for submission for confirmation of
pathological review and determination of 1p and 19q deletion status

- Patients must currently meet ≥ 1 of the following criteria*:

- Uncontrolled symptoms, defined as any of the following:

- Headaches associated with mass effect

- Uncontrolled seizures despite two different antiepileptic drug regimens
(i.e., two antiepileptic drugs tested either sequentially or in
combination)

- Focal neurological symptoms

- Cognitive symptoms or deficits

- Tumor progression by serial MRIs, defined as any of the following:

- New or progressive enhancement

- New or progressive T2 or FLAIR signal abnormality

- Age ≥ 40 years

- NOTE: *Patients < 40 years of age whose only symptom of low-grade glioma is seizures
that are well-controlled on antiepileptic drugs AND who have no evidence of
radiographic progression are not eligible.

- Patients who have undergone gross total resection and have no detectable residual
disease are eligible

- No pilocytic astrocytoma, ganglioglioma, pleomorphic xanthoastrocytoma, or
dysembryoplastic neuroepithelial tumors

PATIENT CHARACTERISTICS:

- Karnofsky performance status 60-100%

- WBC ≥ 3,000/mm^3

- ANC ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Hematocrit ≥ 30%

- Bilirubin ≤ 2 times upper limit of normal (ULN)

- AST and ALT ≤ 3 times ULN

- Creatinine ≤ 2.0 times ULN

- Not pregnant or nursing

- Negative pregnancy test

- Able to undergo MRI with and without contrast

- No other malignancy within the past 5 years, except for nonmelanoma skin cancer or
cervical carcinoma in situ

- No uncontrolled infection

- No known HIV positivity

- No medical disorder that would increase risks associated with radiotherapy and
temozolomide

- No other disorder that would limit life expectancy to < 5 years

PRIOR CONCURRENT THERAPY:

- No prior radiotherapy, cytotoxic chemotherapy, radiosurgery, or investigational
therapy directed at the brain tumor

- Any number of prior surgical procedures for the brain tumor allowed

- No prior radiotherapy to the head unless the radiotherapy ports entirely excluded the
brain

- At least 2 weeks since any prior brain surgery (e.g., stereotatic biopsy, open
biopsy, or resection)

- At least 6 weeks since prior MRI and chest x-ray

- If resection is performed, an MRI after surgery is required