Radioimmunoassay for carcinoembryonic antigen as an adjunct to liver scan in the detection of liver metastases from digestive-tract cancer.

In a series of 327 patients with primary GI malignancies, the occurrence of hepatic metastases was correctly detected in 70% of 113 cases by focal defects in the radiocolloid scintiscan. Only 1% of false positives were observed among the 214 patients without hepatic metastases. For these patients, the predictive value of the liver scan was 97%, and the overall accuracy, 89%. A composite test formed by disjoining focal radionuclide defects with the combination of elevated CEA and hepatomegaly, or elevated CEA and high alkaline phosphatase activity, exhibited a predictive value of 92% and an overall accuracy of 92%. Formation of such a composite test may be useful for preserving high accuracy when very strict scintigraphic criteria for metastases are employed.