<qa>  What must patients have discontinued chemotherapy, immunotherapy or other investigational agents used in adjuvant- Patients must have discontinued chemotherapy, immunotherapy or other investigational agents used in the adjuvant setting 4 weeks prior to randomization and recovered from adverse events due to those agents; mitomycin and nitrosoureas must have been discontinued at least 6 weeks prior to entering the study; patients must have discontinued radiation therapy 2 weeks prior to entering the study and recovered from any adverse events associated with treatment; prior surgery must be 4 weeks from randomization and patients must be fully recovered from post-surgical complications 