Diagnosis of tumors of the parotid gland with anti-CEA immunoscintigraphy.

Twenty-nine consecutive patients with a palpable unilateral tumor in the parotid gland region had scintigraphy 22-28 hr after they were injected with 111In-labeled monoclonal anti-carcinoembryonic antigen (CEA) antibody (F023C5). Two patients were imaged at 48 hr also, and one patient was imaged additionally with single-photon emission CT. Twenty-seven of the patients had surgery within 2-3 weeks. The serum CEA concentrations were normal in 27 of 29 patients. Immunoglobulin G human anti-murine-antibody concentrations were elevated in three of 20 patients. Ten patients had scintigraphic findings suggesting a malignant tumor, six of them had histologically proved malignant tumors. The tumors associated with positive immunoscintigrams were stained immunohistochemically with anti-CEA, and four of the malignant tumors were positive in immunohistochemical staining. The results suggest that nonspecific anti-CEA-antibody imaging is helpful in predicting the presence of a malignant tumor in the parotid area. The radioantibody method could provide useful clinical information that has a high negative predictive value.