Immediate Compared With Delayed Chemotherapy in Advanced Colorectal Cancer Without Signs or Symptoms of Disease

RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining more than one drug may kill more tumor cells. It is not yet known which treatment regimen is more effective for colorectal cancer. PURPOSE: Randomized phase III trial to compare the effectiveness of immediate with delayed fluorouracil plus leucovorin in treating patients with advanced colorectal cancer without signs or symptoms of disease.