Serum CEA testing in the post-operative surveillance of colorectal carcinoma.

Six hundred and sixty-three patients were followed with serial serum CEA measurements in addition to routine clinical surveillance after radical resection of colorectal carcinoma. Of 626 available for analysis, 366 (58.4%) remained clinically free of recurrence and had a normal CEA (less than 20 ng ml-1) throughout and 89 (14.2%) had a temporary non-progressive rise in CEA with no evidence of secondary disease. Of 171 patients who developed proven or suggestive recurrence, 114 had a preceding rise in the serum CEA and in further 21 the CEA rose simultaneously with recurrence. In 36 patients secondary disease was detected while the CEA was still within normal limits. CEA was more effective as an early index of distant metastasis, thus in 76% of those patients with a preceding rise in CEA, the secondary disease was disseminated, whereas only 20% had localised recurrence. The pattern of rise in CEA was of no practical value in distinguishing localised from distant recurrence.