OBJECTIVES: I. Determine response rate, response duration, and survival of patients with AIDS-related or immunocompetent primary central nervous system lymphoma after treatment with oral lomustine and procarbazine, filgrastim (G-CSF), and radiotherapy. II. Determine toxicity of this combined modality in these patients. III. Determine quality of life of these patients.

OUTLINE: Patients are stratified by CD4 count (50/mm3 and under vs greater than 50/mm3). Patients receive oral lomustine on day 1 and oral procarbazine on days 1-10 and days 22-31. Filgrastim (G-CSF) is administered subcutaneously daily on days 12-21 and days 33-42, until absolute neutrophil counts recover. Patients with a complete response after 6 weeks receive one additional course of chemotherapy prior to radiotherapy. Patients with a partial response, stable disease, or disease progression after 6 weeks proceed to radiotherapy without receiving a second course of chemotherapy. Whole brain radiotherapy is administered daily for 28 days beginning 1-3 weeks following chemotherapy. Quality of life is assessed prior to therapy, at 3 and 6 weeks, and then every 2 months following radiotherapy. Patients are followed every 2 months until death.

PROJECTED ACCRUAL: Approximately 16 patients will be accrued for this study.