PATIENT CHARACTERISTICS: Age: Over 15 Performance status: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: For patients with T4 less than 200 and those with primary brain lymphoma: Creatinine no greater than 2.0 mg/dL (unless entry approved by principal investigator) Other: Serious intercurrent illness must be discussed with the principal investigator Infectious disease consultation required for complex infections Medications for other conditions allowed provided no adverse interaction with protocol therapy occurs No previously diagnosed Kaposi's sarcoma or other malignancy