Hi.
Elevated serum carcinoembryonic antigen(CEA) levels, particularly if the levels exceed 5 ng/ml, are sensitive
for detecting recurrence of a previously diagnosed case of colon cancer. Decreasing levels of CEA from
baseline values can also be used to determine response to treatment (e.g. chemotherapy) of a known case of
colon cancer.
However, CEA is not specific for colon cancer. As such, it cannot be used as the initial test to screen for
colon cancer occurrence. Elevated CEA can also be seen in other cancers, such as those involving the breast,
lungs, and other organs of the digestive system. It can also be elevated in some non-cancerous conditions
such as chronic liver disease,pancreatitis, and ulcerative colitis. Heavy smoking can also cause a transient
increase of this tumor marker.
So now we go to your case: does a CEA of 24 ng/ml mean that you have a high probability of having colon
cancer? It really depends on what the histology of those "precancerous polyps" are. If those polyps
already showed a lot of atypical cells two years ago, then I would highly suspect the elevated CEA to be a
manifestation of overt colon cancer. If the overall histologic picture of those polyps was benign, then I
would look for some other possible causes of an elevated CEA (e.g: Are you a heavy smoker? Do you have liver
disease?) before considering a diagnosis of colon cancer.
Anyway, it is a good thing that you're having the colonoscopy done. Colonoscopy, when combined with
biopsy of any suspicious areas, can provide a more accurate confirmation of cancer than CEA.
I hope the explanations help.
