The CEA blood test is not reliable for diagnosing cancer or as a screening test for early detection of cancer.
CEA testing is a reliable test for recurrent colon cancer if the original cancer produced this protein before treatment.
Most types of cancer do not produce a high CEA. Having a normal CEA level does not mean that you do not have cancer.
CEA levels usually return to near-normal levels within 6 weeks of starting treatment if cancer treatment is successful.
Measuring the amount of CEA in other body fluids, such as abdominal fluid (peritoneal fluid) or the fluid around the brain and spinal cord (cerebrospinal fluid, or CSF), can determine whether cancer has spread to that part of the body.