What is the significance of carcinoembryonic antigen (CEA) in colorectal cancer?

The significance of carcinoembryonic antigen (CEA) in colorectal cancer primarily lies in its role as a tumor marker for monitoring treatment response. CEA is a glycoprotein that is often elevated in individuals with colorectal cancer, and its levels can be measured through blood tests.

After treatment, particularly surgery or chemotherapy, tracking the CEA levels can provide valuable information about how effective the treatment has been. A decreasing CEA level generally indicates that the treatment is working and that the tumor is responding positively, while stable or increasing levels may suggest disease progression or recurrence.

In this context, CEA is not traditionally used for the initial diagnosis of colorectal cancer, because it is not specific or sensitive enough to confirm the presence of cancer on its own. Rather, it serves as a prognostic and monitoring tool post-diagnosis and treatment.

Additionally, CEA does not provide information about hormone receptor positivity, as it is not associated with hormone receptor status, nor does it give insights into the tumor's genetic characteristics. Its primary utility remains in treatment monitoring, reinforcing the importance of CEA in the management of colorectal cancer.