RATIONALE: Diagnostic procedures, such as ultrasound, x-ray, colonoscopy, CT scan, and CEA assessment, may help monitor a patient's response to surgery. It is not yet known which follow-up regimen is more effective in patients who have undergone surgery for colorectal cancer.

PURPOSE: This randomized phase III trial is comparing two types of follow-up care with or without CEA assessments to see how well they work in patients who have undergone surgery for stage II or stage III colorectal cancer.

OBJECTIVES:

• Evaluate the efficacy of reinforced versus standard follow-up care and the utility of follow-up CEA assessments in patients with fully resected stage II or III colorectal cancer.

OUTLINE: This is a multinational/multicenter study. Patients are randomized to 1 of 2 follow-up arms.

• Standard follow-up: Patients undergo clinical assessments every 3 months until year 3 and every 6 months until year 5. They are then assessed at least yearly thereafter. Patients undergo abdominal ultrasound every 3 months until year 3 and then every 6 months until year 5; chest x-ray every 6 months until year 3 and then annually until year 5; and colonoscopy at 3 years after surgery then every 3 to 6 years thereafter.
• Reinforced follow-up: Patients undergo clinical assessments every 3 months until year 3 and every 6 months until year 5. They are then assessed at least yearly thereafter. Patients undergo alternate assessments every 3 months comprising thoraco-abdomino-pelvic CT scan or abdominal ultrasound until year 3 and then every 6 months until year 5. They also undergo colonoscopy at 3 years after surgery then every 3 to 6 years thereafter.

Patients undergo a second randomization to 1 of 2 follow-up arms at the beginning of the study.

• CEA measurement: Patients undergo measurement of CEA levels every 3 months until year 3, every 6 months until year 5, and at least yearly thereafter.
• No CEA measurement: Patients do not undergo CEA measurement. Blood and tissue blocks of normal and tumor tissues are collected for the validation of protein serum, genetics, or immunologic markers predictive for relapse.

DISEASE CHARACTERISTICS:

• Pathologically confirmed adenocarcinoma of the colon or rectum

  • Stage II or III disease
  • No distant metastatic disease

• Has undergone curative resection for no residual tumor

• Carcinoembryonic antigen (CEA) ≤ 1.5 x upper limit of normal after surgery

PATIENT CHARACTERISTICS:

• WHO performance status 0-1
• Not pregnant or nursing
• Fertile patients must use effective contraception
• No inflammatory bowel disease
• No other malignancy within the past 5 years except basal cell carcinoma of the skin and/or carcinoma in situ of the cervix
• No genetic syndromes

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics