Indium 111 ZCE-025 immunoscintigraphy in occult recurrent colorectal cancer with elevated carcinoembryonic antigen level.

We investigated the utility of scanning with indium 111 labeled to monoclonal antibody in 13 patients after curative resection of colorectal cancer who had elevated carcinoembryonic antigen levels and negative results of clinical workup. Each patient received 1 mg of anti-carcinoembryonic antigen monoclonal antibody type ZCE 025 labeled with 5.5 mCi of 111In, plus 9 to 39 mg of the same antibody unlabeled. Patients underwent scanning 3 to 7 days after infusion by planar and emission computed tomography. ZCE-025 monoclonal antibody imaging detected tumor recurrence or metastasis in 11 of 13 patients. In one patient the monoclonal antibody scan gave a true-negative result, and in one patient the monoclonal antibody scan failed to disclose a metachronous cecal primary. Tumor sites identified were the pelvis (2 patients), abdominal wall (2), retroperitoneum (1), lymph nodes (3); liver (2), bone (2), and lung (1). The accurate localization of colorectal carcinoma recurrences by means of 111In ZCE-025 monoclonal antibody demonstrates the usefulness of this diagnostic agent in the setting of elevated carcinoembryonic antigen level and negative results of clinical and radiologic workup.