• Twenty patients with 21 primary colorectal adenocarcinomas were studied with 2 mCi (7.6 ×107 becquerels) of indium-labeled monoclonal antibody (200 μg) specific for carcinoembryonic antigen (CEA). Fifteen lesions (71%) were visualized by gamma camera scintigraphy at 48 hours postinjection. Tumors that were identified by immunoscintigraphy were large (38.10±17.76 cm3 vs 6.00±1.65 cm3), had a grossly fungating component, had a high content of CEA by enzyme immunoassay (12.9±3.6 μg/g vs 3.3±1.7 μg/g), and had an apical and/or intraluminal staining pattern on immunohistologic section. Patients whose tumors were visualized had a low serum CEA level (1.9±0.4 ng/mL vs 14.6± 8.0 ng/mL). Prospective selection of patients for follow-up imaging or therapy with radiolabeled monoclonal antibodies may be feasible using these measurements.
(Arch Surg 1986;121:1315-1319)