CEA stands for carcinoembryonic antigen. It is a protein found in the blood.
In some cancers, including bowel cancer, the levels of CEA are higher than normal. Because of this CEA is called a tumour marker. But, there can be reasons other than cancer for raised CEA levels.
If you have bowel cancer doctors may measure CEA levels to:
- Monitor your response to treatment
- Watch for signs of cancer coming back after treatment
You may have a CEA test when you are first diagnosed with bowel cancer. If your levels are high the CEA test may be a useful way of monitoring your response to treatment. If your CEA levels are normal then the test isn't useful and won't be used for you.
Generally, if bowel cancer treatment is working, CEA levels should go down. But, there may be a temporary increase in the blood levels of CEA during some treatments such as chemotherapy or radiotherapy. This rise is probably caused by cancer cells, which have been damaged by the treatment, breaking down and releasing CEA protein into the blood.
After your treatment is over, a normal CEA level can be helpful in showing that the cancer hasn't begun to grow again. If the CEA level is high or rising your doctor is likely to arrange tests to check that the cancer isn't coming back.
We don't know for sure if routinely checking CEA levels after treatment is useful. A large clinical trial is looking into this but it will be several years before the results are known.
UK guidelines don't recommend routine CEA testing as part of follow up after treatment. But, many doctors choose to use the test.