To estimate the response rate, overall and disease-free survival, toxicities, factors associated with outcome, and effect on quality of life in patients with AIDS-related primary CNS lymphoma treated with CHOD (cyclophosphamide, doxorubicin, vincristine, and dexamethasone) plus filgrastim (granulocyte-colony stimulating factor; G-CSF) and external beam irradiation. To determine other clinical markers present in this patient population.