Observation or Radiation Therapy With or Without Combination Chemotherapy in Treating Patients With Low-Grade Glioma

Overview

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. It is not yet known whether radiation therapy combined with chemotherapy is more effective than radiation therapy alone in treating patients with low-grade glioma. PURPOSE: Phase II/III trial to evaluate observation and to compare the effectiveness of radiation therapy with or without combination chemotherapy in treating patients with low-grade glioma.

OBJECTIVES: * Identify the overall survival of low-risk adult patients with supratentorial low-grade glioma who are observed postoperatively. * Compare the overall survival of high-risk adult patients with supratentorial low-grade glioma who receive postoperative external beam radiotherapy with or without procarbazine, lomustine, and vincristine (PCV) chemotherapy. * Compare the toxic effects of postoperative radiotherapy with or without PCV chemotherapy in patients with unfavorable low-grade glioma. OUTLINE: This is a randomized study. Patients are stratified according to tumor subtype (astrocytoma \[mixed-astro dominant or equal astro/oligo mix\] vs oligodendroglioma \[mixed-oligo dominant\]), age (younger than 40 vs at least 40), Karnofsky performance status (60-80% vs 90-100%), and contrast enhancement on preoperative scan (present vs absent). Patients with low-risk disease (younger than 40 years old whose tumors have been surgically removed) are assigned to arm I. Patients with high-risk disease (at least 40 years old or who have had incomplete tumor removal) are randomized to arm II or III. * Arm I (low-risk patients): Patients are observed. Patients may receive treatment if tumor recurs. * Arm II (high-risk patients): Patients receive daily external beam radiotherapy 5 days a week for 6 weeks. * Arm III (high-risk patients): Patients receive radiotherapy as in arm II followed by chemotherapy 1 month later. Chemotherapy consists of oral lomustine on day 1, vincristine IV on days 8 and 29, and oral procarbazine on days 8-21. Each course of chemotherapy lasts 8 weeks. Patients may receive up to 6 courses of chemotherapy. Patients are followed every 4 months for 1 year, every 6 months for 2 years, and then annually thereafter. PROJECTED ACCRUAL: Approximately 252 patients will be accrued within 5.25 years.