OBJECTIVES: I. Evaluate the complete remission rate and survival of patients with lymphoproliferation following organ transplantation treated with a defined sequential approach: modification of immunosuppression, with surgery or limited radiotherapy for an isolated site of disease; interferon alfa; and chemotherapy (ProMACE-CytaBOM; cyclophosphamide, doxorubicin, etoposide, prednisone, cytarabine, bleomycin, vincristine, methotrexate).