The use of CEA as an early indicator for gastrointestinal tumor recurrence and second-look procedures.

Since 1972 plasma CEA levels of 25 cancer patients have been assayed to evaluate the reliability of CEA as an early indicator of recurrent gastrointestinal cancer. Identification of significant elevations in CEA levels required definition of exactly what a given value meant. Intraassay and interassay accuracy was determined and graphed as a CEA NOMOGRAM, which measures the observed CEA level against the 95% confidence limits for that observation and thus can be used to identify statistically significant increases. A statistically significant rise above a baseline value established by the NOMOGRAM proved to be a correct indicator of tumor recurrence in 22 (88%) of 25 patients who underwent second-look intraabdominal operations (22 colorectal, 2 gastric, and 1 pancreatic). In each case, other accepted procedures, such as liver enzymes, scans, and x-rays, were nondiagnostic. Of the 22 patients with proved tumor recurrence, 16 (73%) had distant metastases and 6 (27%) had localized tumors. One patient remains tumor-free three years after second-look operation and has had no significant change in CEA levels. More frequent serial CEA determinations combined with sound clinical judgment should facilitate earlier detection of recurrent gastrointestinal cancer.