CEA stands for carcinoembryonic antigen. CEA is a protein found at low levels in the blood. A test involves taking blood from a vein to measure the levels of CEA.

With some types of cancer, such as cancers of the bowel, levels of CEA may be higher than normal. Other cancers that may cause higher levels of CEA include cancers of the lung, pancreas, stomach, ovaries, breast and thyroid.

Because CEA is raised in some types of cancer it is called a tumour marker. But, there can be other causes for a raised CEA level. Smokers tend to have higher levels than non-smokers. Non-cancerous conditions that cause inflammation such as pancreatitis, cirrhosis of the liver and bowel diseases can also raise levels above normal.