[Tumor Diagnosis by Immunoscintigraphy with Anti-CEA Antibodies (Tc-99m MAK BW 431/26)]

We evaluated the clinical application of the monoclonal antibody MAb, BW 431/26, which is easy to label with Tc-99m for tumor localization. This is an anti-CEA antibody and a murine immunoglobulin (Ig G1, Isotype). We investigated patients with colorectal carcinoma (n = 14), with colorectal carcinoma recurrences (n = 24), breast carcinoma (n = 2), stomach carcinoma (n = 1), carcinoma of the urinary bladder (n = 3), lung carcinoma (n = 2) and patients with an elevated CEA level. In primary colorectal tumors (n = 14) all carcinomas were correctly localized by IS and ECT technique. In these patients the diagnosis was already known. The planar pictures showed a false negative result in 3 patients. In patients with colorectal recurrences the investigations were performed twice in 2 patients and three times in 1 patient. In these 31 ECT investigations we found 17 true positive results, 12 true negative results, 1 false positive result and 1 false negative result. The lesions were already visualized within 4 to 6 hours, but 24-hour pictures are desirable. SPECT pictures are absolutely necessary because sensitivity is considerably improved thereby. Elevated CEA levels increase the probability of a positive IS low CEA levels do not exclude positive tumor visualization. HAMA was found in only 1 patient, but follow-up investigations are indicated.