Radiation Therapy or Combination Chemotherapy in Treating Patients With Clinically or Radiologically Progressive Low-Grade Gliomas

RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Drugs used in chemotherapy, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. PURPOSE: This clinical trial is studying giving radiation therapy or combination chemotherapy to see how well it works in treating patients with clinically or radiologically progressive low-grade gliomas.