Use of 123-I Radiolabelled F(AB’)2 Fragments of Anti-CEA Monoclonal Antibody for the Detection of Primary and Metastatic Gastrointestinal Carcinomas

F(ab’)2 fragments of an anti-CEA monoclonal antibody were radiolabelled with 123-I and used to study eleven patients with various types of gastrointestinal carcinomas. The antibody scans detected primary or metastatic disease in 4 out of 7 patients with known disease and they suggested the existence of disease in 3 cases, in sites not detected by conventional techniques. In 1 patient, liver metastases were detected with the antibody scan 3 months earlier than with CT scan examination. Absence of disease was confirmed in 3 patients in complete remission. These results indicate that external scintigraphy using 123-I labelled F(ab’)2 fragments of anti-CEA monoclonal antibodies may be a useful tool in monitoring patients with gastrointestinal tumours in terms of confirming the results of conventional methods or revealing disease sites undetected by conventional radiology.