Radioimmunodetection of Primary and Metastatic Ovarian Cancer Using Radiolabeled Antibodies to Carcinoembryonic †̃2

131I-Labeledgoat immunoglobulin G (IgG) prepared against carcinoembryonic antigen (CEA) was administered at an aver age dose of 1.0 mCi (180 to 250 @glgG protein) to patients with ovarian tumors in order to evaluate this method of tumor detection and localization , termed the radioimmunodetection of cancer. All primary cancers in 13 patients could be localized, whereas the metastases in six of nine cases could be imaged by external scintigraphy. However, only two of these cases showed metastatic spread by more conventional diagnostic techniques, including computer-assisted tomography, ultra sonography, and angiography. Successful tumor radiolocali zation appeared to depend on tumor size, with lesions smaller than 2 cm in diameter not being detected. Tumors containing a CEA concentration above 115 ng/g, including a benign neoplasm, could be localized with radioactive anti-CEA anti bodies. Administration of radioiodinated normal goat lgG to four patients with malignant or benign ovarian tumors failed to show tumor radioimmunodetection. One of these cases sub sequently demonstrated a 4x 4-cm tumor after receiving specific radiolabeled anti-CEA lgG. This study shows that ovar ian neoplasms containing CEA can be detected and localized by external photoscanning after the application of radioiodi nated antibodies to CEA and that, in this small series of pa tients, primary and secondary tumors could be detected in 100 and 67% of the cases, respectively.