Are cea markers reliable for metastic colon cancer ?

Cautiously: It's useful as one tool among many to follow the course, but it isn't useful for making a de novo diagnosis.

Depending how used: CEA first identified in 1965 by Phil Gold and Samuel O. Freedman in human colon cancer extracts. Thought to be valuable for dx colorectal Ca but the glycoprotein is also expressed in inflamed tissue so that smoking and enema can cause rise. Best used for monitoring so that if present in primary and rises it represents treatment failure and if diminishes during treatment it represents a response.

Monitoring tool yes: Besides malignancy CEA levels are elevated in several benign conditions , previous low or normal CEA to elevated levels is significant finding is most likely an indication of recurrence of tumor ( metastasis )

Depends: Some tumors produce the metered antigen and some don't. The more aggressive one often do not. So there a lot of false negatives

Sometimes: If your CEA was elevated at the time of diagnosis, then came down to normal postoperatively, a second rise can be due to recurrence of disease.

CEA: Carcinoembryonic antigen=CEA This is what is called an onco-fetal antigen, meaning something that is expressed in early development and then also expressed by some tumors, most commonly colon and breast. But not all tumors express it. The level roughly correlates with the mass of tumor cells, but is very individual. Not all Ca express. Rate of change useful for monitoring for recurrences.