A Study Using Radiation Therapy and Temozolomide to Treat Glioblastoma in Patients Over 70

Inclusion Criteria:

1. Participants must have histologically confirmed glioblastoma/gliosarcoma.
2. Tumor o6-methylguanine-DNA-methyltransferase promoter methylation status must be determined
3. Participants must not have had any prior therapy for glioblastoma multiforme including radiation or chemotherapy.
4. Participants must be \> 70 years of age.
5. Participants must have life expectancy greater than 6 months.
6. Karnofsky performance status \> 60 (ECOG \< 2).
7. Patients must have normal organ and marrow function

   * Leukocytes \> 3,000/microliter
   * Absolute neutrophil count \> 1,500/microliter
   * Platelets \> 100,000/microliter
   * Total bilirubin within normal institutional limits 12
   * aspartate aminotransferase test(SGOT)/alanine aminotransferase test(SGPT) \< 2.5 X institutional upper limit of normal
   * Creatinine within normal institutional limits or creatinine clearance \> 60 mL/min/1.73 m2 for subjects with creatinine levels about institutional normal
8. Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

1. Participants may not be receiving any other study agents.
2. Participants may not have had chemotherapy wafer placement at surgery.
3. History of allergic reactions attributed to compounds of similar chemical or biologic composition to temozolomide.
4. Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
5. Individuals with a history of a different malignancy are ineligible except for the following circumstances. Individuals with a history of other malignancies are eligible if they have been disease-free for at least 3 years and are deemed by the investigator to be at low risk for recurrence of that malignancy. Individuals with the following cancers are eligible if diagnosed and treated within the past 5 years: cervical cancer in situ, and basal cell or squamous cell carcinoma of the skin.
6. HIV-positive individuals on combination antiretroviral therapy are ineligible because of the potential for pharmacokinetic interactions with temozolomide. In addition, these individuals are at increased risk of lethal infections when treated with marrow-suppressive therapy. Appropriate studies will be undertaken in participants receiving combination antiretroviral therapy when indicated.