What is a CEA blood test?

A CEA test, also known as a carcinoembryonic antigen test, is a medical procedure during which the blood levels of the CEA protein are measured, according to WebMD. It is performed on patients who may suffer from cancer of the colon, rectum, lungs, pancreas, ovaries or breasts.

The CEA protein is normally produced in fetuses before birth, states WebMD. It doesn't normally appear in the blood of healthy adults. The CEA test is performed in order to check how much a form of cancer has spread, to verify if cancer has reoccurred after treatment, and to see whether the treatment of colon cancer has been successful.