Bevacizumab and Temozolomide in Treating Older Patients With Newly-Diagnosed Glioblastoma Multiforme or Gliosarcoma

RATIONALE: Monoclonal antibodies, such as bevacizumab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or carry tumor-killing substances to them. Drugs used in chemotherapy, such as temozolomide, also work in different ways to kill tumor cells or stop them from growing. Giving bevacizumab together with temozolomide may be a better way to block tumor growth. PURPOSE: This phase II trial is studying how well giving bevacizumab and temozolomide together works in treating older patients with newly diagnosed glioblastoma multiforme or gliosarcoma.