Carcinoembryonic Antigen (CEA) in colorectal cancer follow-up

Colorectal cancer follow-up aims to detect recurrent disease as soon as possible, since earlier detection of recurrent disease is associated with greater chances for cure. A part of follow-up is the measurement of Carcinoembryonic Antigen (CEA) in the blood of the patient. This tumor marker is increased in case of new disease activity (i.e., recurrent disease) in about 80% of patients. However, it is not clear how often CEA must be determined and how an increase in CEA should be interpreted. This thesis focuses on the role of CEA in colorectal cancer follow-up. Primarily, a phase-2 trial was conducted to examine how often CEA should be checked regularly, and which CEA increase is sensitive for detecting recurrences. Using the findings of this trial, a new follow-up protocol was constructed, and a randomized study has been rolled out in 11 hospitals. All patients that were treated for colorectal cancer were checked along the lines of the Dutch follow-up guideline (“standard of care”) first, and thereafter they were checked using a new protocol with high-frequency CEA measurements. 3223 patients were included. The promising results show that by making use of the new follow-up protocol, more recurrences are detected and these recurrences have significantly higher curable options than when patients are monitored in accordance with the Dutch guideline. Additional studies in this thesis have shown that the new follow-up protocol is cost effective and is appreciated by patients. The authors now want to focus on the survival effects of the new follow-up protocol.