Dukes B2-C colorectal cancer patients who had no evidence of disease at the end of their front line treatment (surgery and adjuvant radio-chemotherapy, if indicated) are eligible for the trial and randomized to two different surveillance programs. These programs differ greatly in the frequency of diagnostic imaging. They have similar schedules of physical examinations and carcinoembryonic antigen (CEA) assessments. Patients will receive baseline and yearly health-related quality of life (HR-QoL) questionnaires. Primary outcomes are overall survival and QoL.

Minimal program for colon cancer: Office visit and CEA at 4,8,12,16,20,24,30,36,42,48, and 60 months. Colonoscopy at 12, and 48 months. Liver echography* at 8, and 20 months.

Intensive program for colon cancer: Office visit, CBC, CEA+CA 19.9 at 4,8,12,16,20,24,30,36,42,48, and 60 months. Colonoscopy at 12, 24, 36, 48,and 60 months. Liver echography* at 4,8,12,16,24,36,48, and 60 months. Chest X-ray at 12,24,36,48,and 60 months.

* Abdominal-pelvis C.T., as an alternative to echography, was a 2° level exam only (doubtful results of physical examination or echography; increasing levels of CEA; predictable poor sensitivity of echography due to obesity or other anatomic-clinical conditions)

Inclusion Criteria:

• Patients with histologically proven adenocarcinoma of the colon or rectum with Dukes Astler-Coller modification stage B2-C who had been treated with curative intent (radical excision ± adjuvant radio-chemotherapy) .
• Eligible patients had to be free of known cancer prior to study entry as attested by negative results of endoscopy, liver ultrasonography, chest roentgenography and serum CEA level performed < 4 months before randomization

Exclusion Criteria:

• Inability to undergo testing (disability, allergy to contrast agents, etc.) and patients geographically not amenable to full follow-up.
• Patients enrolled onto any other research protocol that requires strict adherence to any specific follow-up practice.
• A history of any previous malignancy in the last 10 years (other than carcinoma in situ of the cervix or non-melanoma skin cancer).
• No informed consent to participate in the trial according to local regulatory guidelines.