Carcinoembryonic Antigen Immunoscintigraphy Complements Mammography in the Diagnosis of Breast
Carcinoma
David Goldenberg, Sc.D., M.D., Hani Abdel-Nabi, M.D., Ph.D., Cynthia Sullivan, M.S., M.B.A., Aldo Serafini, M.D., David Seldin, M.D., Bruce Barron, M.D., Lamk Lamki, M.D., Bruce Line, M.D., William Wegener, M.D., Ph.D.
BACKGROUND: An adjunctive noninvasive test that is predictable and highly specific for breast carcinoma would complement the high false-positive rate of mammography in certain patients.
METHODS: This prospective, multicenter study evaluated the accuracy, safety, and immunogenicity of carcinoembryonic antigen (CEA) antibody imaging in women with known or suspected breast carcinoma. Scintigraphic breast images were obtained approximately 3-8 hours after administration of the technetium 99m (99mTc) labeled anti-CEA Fab' and correlated with histopathology.
RESULTS: The 99mTc labeled anti-CEA Fab' detected tumor CEA expression in 46 of 49 women (94%) initially entered with known primary breast carcinoma regardless of histology or serum CEA levels. In women scheduled for biopsy confirmation of mammographic and physical examination findings, 104 99mTc labeled anti-CEA Fab' studies had a sensitivity of 61% (17 of 28 cases) and a specificity of 91% (69 of 76 cases). In total, 99mTc labeled anti-CEA Fab' detected 52 of 62 invasive ductal carcinomas, 5 of 5 invasive lobular carcinomas, and 3 of 6 noninvasive tumors. (2 ductal carcinomas in situ and 1 intracystic papillary carcinoma.) Tumor size significantly affected sensitivity. (p=0.041), with 11 of 14 missed lesions £T1, and proliferative histology significantly affected specificity (p=0.012), with 5 of 7 false positive tumors being premalignant. In 50 breast carcinoma patients, 99mTc labeled anti-CEA Fab' also demonstrated axillary lymph node involvement regardless of CEA serum levels, with a sensitivity of 80% when more than three lymph nodes were positive. No immune response or other meaningful side effects occurred.
CONCLUSIONS: 99mTc labeled anti-CEA Fab' had high specificity and positive predictive values for breast carcinoma and the majority of false-positive studies were associated with an increased risk of malignancy. Improved imaging techniques, including dedicated gamma cameras for breast and axillary lymph node imaging, will likely improve the test's sensitivity for smaller lesions.