Carcinoembryonic antigen radioimmunodetection in the evaluation of colorectal cancer and in the detection of occult neoplasms

Abstract Radioimmunodetection of colorectal cancer was evaluated in 51 patients by injecting 131 I-labeled goat antibody immunoglobulin G against carcinoembryonic antigen and performing total-body photoscans with a gamma scintillation camera 24 and 48 h later. The scintigrams were then processed by computer to subtract the images of the 99m -Tc-serum albumin and pertechnetate administered, which reject background and nontarget radioactivity, from the 131 I-antibody scans. The results indicate that radioimmunodetection is a safe and a potentially clinically useful cancer detection method, which in this study demonstrated primary colorectal carcinomas in 10 of 12 (83%) of the patients evaluated preoperatively and between 87% (46 of 53) and 92% (49 of 53) of known metastatic tumor sites. Thus, the method's overall sensitivity (true-positive rate) was 86%–91% on a tumor-site basis. A false-negative rate of between 9% and 14% and a false-positive rate of