Gefitinib and Radiation Therapy in Treating Patients With Glioblastoma Multiforme

Inclusion Criteria: * Histopathologically confirmed glioblastoma multiforme (with areas of necrosis) * Diagnosis must be made by surgical biopsy or excision * The tumor must be supratentorial in location * The patient must have recovered from the effects of surgery, post-operative infection, or other complications before study entry * Radiotherapy must begin =\< five weeks after surgery, and Iressa (gefitinib) must begin one week prior to radiotherapy * Patients must have an estimated survival of at least 8 weeks * Zubrod performance status of 0-1 * A diagnostic contrast-enhanced magnetic resonance imaging (MRI) or computed tomography (CT) scan must be performed preoperatively and postoperatively prior to the initiation of radiotherapy; preoperative and postoperative scans must be the same type * Patients diagnosed only by stereotactic biopsy do not require the postoperative scan * Patients unable to undergo magnetic resonance (MR) imaging because of non-compatible devices can be enrolled, provided pre and postoperative CT scans are obtained and are of sufficient quality * Hemoglobin \>= 10 grams * Absolute neutrophil count \>= 1500 (ANC) per mm\^3 * Platelets \>= 100,000 per mm\^3 * Blood urea nitrogen (BUN) =\< 25 mg * Creatinine =\< 1.5 mg * Bilirubin =\< 2.0 mg * Serum glutamate pyruvate transaminase (SGPT) or serum glutamic oxaloacetic transaminase (SGOT) =\< 2 x normal range * Patients must consent to submission of their tissue/serum * The patient must sign a study-specific informed consent prior to study entry; if the patient's mental status precludes his/her giving informed consent, written informed consent may be given by the responsible family member Exclusion Criteria: * Recurrent or multifocal malignant gliomas * Metastases detected below the tentorium or beyond the cranial vault * Major medical illnesses or psychiatric impairments which, in the investigator's opinion, will prevent administration or completion of protocol therapy * Previous radiotherapy to the head or neck (except for T1 glottic cancer), resulting in overlap of radiation fields * Active connective tissue disorders, such as lupus or scleroderma which, in the opinion of the treating physician, may put the patient at high risk for radiation toxicity * Previous malignancies, except for non-melanomatous skin cancers and carcinoma in situ of the uterine cervix or bladder, unless disease-free for \>= 3 years * Prior chemotherapy or radiosensitizers for cancers of the head and neck region * Patients with known acquired immune deficiency (AIDS); patients with AIDS require complex therapeutic regimens; the pharmacokinetic interactions of these regimens with ZD 1839 are unknown and therefore, pose a safety risk related to excess toxicity or interference with anti-viral effectiveness * Patients with known multiple sclerosis, as these patients may have decreased tolerance for radiation therapy to the brain * Pregnant or lactating women, due to possible adverse effects on the developing fetus or infant due to study drug * Patients treated on any other clinical protocols within 30 days prior to study entry or during participation in the study