OBJECTIVES: I. Determine the maximum tolerated dose and dose limiting toxicity of vincristine given as an IV push dose in combination with continuous infusion cyclosporine and oral etoposide concurrent with and prior to radiotherapy in children with newly diagnosed primary intrinsic brain stem glioma. II. Determine the incidence and severity of other toxicities of vincristine in this regimen in these patients. III. Determine a safe and tolerable dose of vincristine under these conditions to be used in phase II studies. IV. Seek preliminary evidence of antitumor activity in this setting in these patients.