Carcinoembryonic Antigen (CEA) is a protein that is normally found in the developing fetus. However, elevated levels of CEA in the blood can indicate the presence of certain types of cancer, including colorectal, pancreatic, and lung cancer. The CEA blood test is a simple and non-invasive way to detect these cancers and monitor their progression. Results of the CEA blood test can be used to guide treatment decisions and track the effectiveness of treatment. Overall, the CEA blood test is an important tool in the early detection and management of cancer.