OUTLINE: This is a randomized, multicenter study. Patients are stratified according to participating center. Patients are randomized to one of two treatment arms. Arm I: Patients receive interferon alfa subcutaneously daily. Arm II: Patients receive interferon alfa as in arm I plus oral isotretinoin daily. Treatment continues for up to 1 year in the absence of disease progression or unacceptable toxicity. Patients are followed until death.