Serum CEA levels fluctuate over time in healthy individuals, and the intraindividual variation has been reported to be about 30% [19].

Why does my CEA level fluctuate?

The most frequent cancer which causes an increased CEA is cancer of the colon and rectum. Benign conditions which can elevate CEA include smoking, infections, inflammatory bowel disease, pancreatitis, cirrhosis of the liver, and some benign tumors in the same organs in which an elevated CEA level indicates cancer.

How quickly can CEA levels rise?

Two distinct patterns of CEA rise were observed: a 'fast' rise in which serum concentrations reached 100 microgram/l within 6 months of the first elevation and a 'slow' rise in which concentrations remained less than 75 microgram/l for at least 12 months.