Carcinoembryonic Antigen (CEA) Test

The Carcinoembryonic Antigen (CEA) test is a specialized blood examination used to detect and measure the concentration of CEA, a protein normally present only during fetal development but re-expressed in certain cancers. Clinically, CEA is one of the most important tumor markers for cancers of the gastrointestinal tract, including cancers of the colon, rectum, stomach, esophagus, liver, and pancreas. It is also used in cases of breast, lung, and prostate cancer.

A rising CEA level is often a sign of cancer progression or recurrence, making it a valuable tool for ongoing monitoring after treatment. When treatment is effective, CEA levels usually decrease, reflecting a positive therapeutic response. Conversely, stable or increasing levels may indicate that therapy is not effective or that the tumor is continuing to grow.

CEA testing is particularly important after cancer surgery or chemotherapy. In many cases, an elevated CEA level may be the earliest indicator of cancer returning—sometimes months before symptoms develop or before recurrence is visible on imaging studies. For patients undergoing long-term cancer care, CEA levels can guide whether more advanced tests like CT or MRI scans are necessary.

Regular monitoring—typically every 1 to 3 months—is recommended for individuals with a history of CEA-producing tumors. Persistent elevations above baseline should always be rechecked promptly to rule out laboratory error and to ensure timely clinical action.

Measures CEA levels in blood to track cancer progression, monitor treatment, and help detect recurrence of gastrointestinal or related cancers.