What is CEA (Carcinoembryonic Antigen) used for in medical tests?

Carcinoembryonic antigen (CEA), similar to CA125, is a type of tumor marker. In fact, CEA is one of the most commonly used tumor markers. Clinically, it may be primarily associated with tumors of epithelial origin or with some tumors of the reproductive system. Generally, for routine physical examinations, it is not recommended to test for this item. However, for some high-risk individuals undergoing early cancer screening, CEA testing may be performed. Additionally, for patients who have already been diagnosed with cancer or are undergoing treatment, CEA can be used to monitor tumor metastasis and recurrence.

The primary method for detecting CEA is through blood sampling. However, whether it is for early cancer screening or for tumor marker testing in specific diseases, this indicator is not used alone. Rather, it is combined with other indicators for comprehensive judgment. It is crucial to understand that all tumor markers are subject to periodic changes rather than a single value detected at a specific time point. For instance, in patients with rectal cancer, even if CEA levels are normal after surgery, they may increase again after one year or even higher after one and a half years. An upward trend in CEA levels generally indicates the possibility of tumor metastasis or recurrence.

However, tumor markers are always reference values. Some patients with significantly elevated tumor markers may not have experienced tumor metastasis or recurrence. Therefore, tumor markers serve as a reference for doctors, and specific situations must be considered in conjunction with the patient's individual circumstances.