The aim is to investigate the efficiency of two follow-up programs after radical surgery for colorectal cancer. Colorectal cancer attacks between 3-5% of the European population during their lifetime, and about 75% of these will have potential curative surgery performed. Follow up after surgery is costly and time consuming for both patients and the Health Care Systems. The intensity of follow up as well as the methods employed vary tremendously from center to centre and from country to country. Until recently the scientific documentation for the cost-effectiveness of follow-up was very sparse, but recent compiling of data indicates that intense follow up can save lives as compared to sporadic follow-up at an acceptable cost. However, the optimal follow-up intervals and the best methods are unknown. Previous results indicate that scanning of the liver and measuring of the tumor-marker CEA may be a way forward. A prospective randomised multicenter study in centers from Denmark (approx. 15), Sweden (approx. 20), Poland (approx. 6), Hungary (approx. 2) and perhaps The Netherlands and UK is starting in 2005 after basic work with protocols, ethical committees now has been finished. This basic work was supported by the Nordic Cancer Union with a grant of 25,000 EUROS. The patients will be randomised to follow-up with CEA, multislice CT scan of the liver and X-ray of the lungs, either 12 and 36 months after surgery or 6, 12, 18, 24 and 36 months after surgery. If recurrence is detected, the patient will be offered the best available treatment either as repeated surgery with curative intent or palliative oncological treatment. Data will be collected electronically via the internet to an already constructed database. The primary efficacy parameter is 3 and 5 years overall and cancer-specific survival. It is planned that recruitment will be at least 2,500 patients, which is feasible in 2 years.