What is carcinoembryonic antigen?

Carcinoembryonic antigen (CEA) is an acidic glycoprotein with antigenic properties characteristic of human embryonic antigens. It primarily exists on the surface of cancer cells derived from endodermal cells and serves as a structural protein of the cell membrane. CEA is formed in the cytoplasm and subsequently secreted through the cell membrane to the extracellular space, entering surrounding body fluids. Therefore, CEA can be detected in various body fluids such as serum, cerebrospinal fluid, and breast milk. CEA was once considered a specific marker for the early diagnosis of colon and rectal cancers. However, extensive clinical experience has revealed that CEA levels also rise in the serum of patients with various other malignancies, including breast cancer and lung cancer. Therefore, carcinoembryonic antigen is a broad-spectrum tumor marker that holds significant clinical value in differential diagnosis, disease monitoring, and evaluation of treatment efficacy for malignant tumors.