ABSTRACT
The role of plasma carcinoembryonic antigen (CEA) monitoring in patients with various stages of colorectal cancer has been debated almost from the time CEA was defined by Gold and Freedman1 in 1965. There are several ways that plasma CEA monitoring could be of benefit in the management of colorectal cancer. For example, a truly sensitive plasma marker that becomes abnormal in patients with clinically asymptomatic disease who would have a high likelihood of cure with surgical resection would certainly be valuable as a tool in screening large populations for primary colon cancer. Another role for CEA monitoring might be in the patient with advanced colorectal cancer in whom changing levels of CEA in the plasma could direct therapy. In such a situation, ideally a CEA decrease would be a sensitive and specific indicator of response to chemotherapy. Likewise, an elevation of plasma CEA would be a reason to abandon the treatment being given and choose another form of regional or systemic therapy for the patient. Finally, in a patient with resected colorectal cancer, CEA elevation might be a means to detect recurrence. Periodic monitoring for CEA elevation postoperatively could be a valuable strategy if an increased CEA level detected recurrent disease at an early and highly treatable stage. This chapter will discuss the evidence for the use of CEA in the management of patients with colorectal cancer, and it will particularly explore the case for use of CEA monitoring in patients with resected colorectal cancer.
