• All-cause mortality [ Designated as safety issue: No ]
  

• Death from colorectal cancer [ Designated as safety issue: No ]
  
• Disease recurrence [ Designated as safety issue: No ]
  

OBJECTIVES:

• Compare all-cause mortality in patients with resected colorectal cancer treated with adjuvant chemotherapy with L-leucovorin and fluorouracil vs observation.
• Compare the recurrence rates in patients treated with this regimen vs observation.
• Compare the effectiveness of a monthly 5-day schedule vs a once weekly schedule of L-leucovorin and fluorouracil in this patient population.

OUTLINE: This is a randomized, open-label, multicenter study. Patients are randomized to receive adjuvant chemotherapy (arm I) or undergo observation only (arm II).

• Arm I: Within 12 weeks of surgery, patients receive L-leucovorin IV followed by fluorouracil IV on days 1-5 every 4 weeks for 6 courses. Alternatively, patients may receive L-leucovorin IV followed by fluorouracil IV on day 1 weekly for 30 weeks.
• Arm II: Patients undergo observation. Patients are followed annually.

PROJECTED ACCRUAL: A total of 2,500 patients (1,250 per arm) will be accrued for this study.

DISEASE CHARACTERISTICS:

• Completely resected stage II or III colorectal cancer
• No distant metastases
• No positive resection margins
• No positive peritoneal washings

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Not specified

Hepatic:

• Not specified

Renal:

• Not specified

Other:

• No clear definite indication for, or contraindication against, systemic chemotherapy with L-leucovorin and fluorouracil

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• No concurrent chemotherapy in observation only arm

Endocrine therapy:

• Not specified

Radiotherapy:

• Concurrent radiotherapy allowed in adjuvant chemotherapy arm provided chemotherapy administered on the once weekly schedule

Surgery:

• See Disease Characteristics