Arm A: Interferon-alpha-2b 20 MIU/m2 for 4 weeks. 5 days a week i.v followed by 48 weeks of treatment with 3 x 10 MIU/m2 s.c Arm B: Interferon-alpha-2b 20 MIU/m2 for 4 weeks. 5 days a week i.v repeated 3 times with 12 treatment-free-weeks between the cycles