Detection of suspected primary lung cancer by scintigraphy with indium-111-anti-carcinoembryonic antigen monoclonal antibodies (type F023C5).

Immunoscintigraphy with 111In-labeled anti-CEA-Mab (F023C5i) was carried out in 66 patients strongly suspected for a primary lung cancer and in 8 control patients suffering from different chest diseases. A sensitivity of 0.90, a specificity of 0.45 and an accuracy of 0.85 were calculated. False-negative results were mainly obtained in patients in whom the size of the lesion was below 2 cm and the tumor was centrally located. All patients affected by small-cell carcinoma were correctly identified. In 89% of the patients, a positive immunoscintiscan was associated with the presence of the antigen in the tumor. False-positive results were observed in control patients suffering from different chest diseases due to the nonspecific uptake of the tracer. The tumor definition was generally better after 120 hr than at an earlier time after injection due to the reduction of background activity. SPECT imaging defined the tumor better in each patient but did not reveal any tumor not seen on planar studies.