OUTLINE: This is a randomized, multicenter study. Patients are stratified according to lymph node involvement (1-3 vs 4 or more), histology (poorly differentiated or undifferentiated vs well or moderately differentiated), and preoperative serum CEA (less than 5.0 ng/mL vs at least 5.0 ng/mL vs unknown). Study therapy must begin within 21-56 days after surgery. Patients are randomized to one of two treatment arms: