[AS PER AMENDMENT 2/12/99: Patients who have received study medication and/or routine protocol visits and procedures for at least 6 months with acceptable compliance are eligible for continued follow-up in an extension phase. The extension phase will continue for at least 1 year from the date when the last patient has been enrolled in the extension phase. Patients originally randomized to IL-2 may continue to receive IL-2 during the extension period, with IL-2 therapy guided on an individual basis. Patients originally randomized to no therapy may continue to receive no therapy during the extension phase.] [AS PER AMENDMENT 7/11/00: Patients demonstrating acceptable compliance with routine visits and procedures during the initial treatment phase and/or extension phase may participate in the long-term follow-up phase which requires follow-up visits at least every 4 months for approximately 5 years. Patients originally randomized to Group 1 or 2 may continue to receive IL-2, with IL-2 therapy guided on an individual basis, during the long-term follow-up phase. Patients originally randomized to Group 3 may continue to receive no therapy during the long-term follow-up phase.]