Each year there are 10,000 new patients with colorectal cancer, in this group 40% develops a recurrence after surgery. Existing techniques to diagnose tumor recurrence after surgery are not reliable enough. We have developed a method to detect cancer-related substances in macrophages. A pilot study showed that it is possible to distinguish healthy persons from patients with first presentation of colon cancer and inflammatory bowel disease when combining the new analysis with inflammatory parameters. The purpose of this study is to investigate the applicability of the new test in the follow up of patients after surgery.