Development and Evaluation of a CEA Algorithm.

Interventions: None. Primary outcome(s): The aim of the study is to create a serum CEA-measurement based algorithm of CEA rising. If the algorithm proves higher sensitivity of detecting recurrence, and therefore higher curable treatment, it can result in an application which helps professionals in health care, mainly general practitioners, with decision making. One should think of decisions like closer monitoring of CEA measurements, additional imaging based on serum CEA measurements (CEA-triggered imaging”) or referring to a specialist Study Design: Non-randomized controlled trial, Open (masking not used), N/A , unknown, Other