Q: What is carcinoembryonic antigen serum test? Why is it done? I have stomach ache for the past 5 days and have loose motion as well. I have lost weight, but I don't have any other problem. Why was this test prescribed to me? I am scared of cancer. Is it a symptom of cancer?

A:Carcinoembryonic antigen (CEA) is a protein that is normally produced during the development of a fetus and is usually absent in the blood of healthy adults. It is associated with certain tumours and is thus used as a tumour marker. The levels may be elevated in both benign (smoking, infections, inflammatory bowel disease, pancreatitis, cirrhosis of the liver) and malignant (cancers of the colon & rectum) states. The levels are also increased in cancers of the pancreas, stomach, breast, lung, and certain types of thyroid and ovarian cancers. Benign disorders usually result in a mild rise (<10 ng/ml). The test is not very effective for screening purposes since early or occult cancers do not raise its blood levels significantly and some types of cancers may never produce a rise. It is measured to: a) Determine how widespread a cancer is, especially cancer of the colon. b) Monitor the success of therapy (as it is expected to fall to normal following chemotherapy or successful surgical removal the tumour) c) Monitor the recurrence of the cancer. Levels > 20ng/ml prior to treatment indicate that the cancer has spread. It is best to repeat the test in the same laboratory while monitoring, as there is variability between results obtained from different laboratories.