Utility of Commercially Available Quantitative hCG Immunoassays as Tumor Markers in Trophoblastic and Non-Trophoblastic Disease

BACKGROUND: The use of quantitative human chorionic gonadotropin (hCG) as a tumor marker is widely accepted despite lack of FDA-approval for oncology. Differences in iso- and glycoform recognition among hCG immunoassays is well established, exhibiting wide inter-method variability. Here, we assess the utility of 5 quantitative hCG immunoassays for use as tumor markers in trophoblastic and non-trophoblastic disease. METHODS: Remnant specimens were obtained from 150 patients with gestational trophoblastic disease (GTD), germ cell tumors (GCT), or other malignancies. Specimens were identified by review of results from physician-ordered hCG and tumor marker testing. Five analyzer platforms were used for split specimen analysis of hCG: Abbott Architect Total, Roche cobas STAT, Roche cobas Total, Siemens Dimension Vista Total, and Beckman Access Total. RESULTS: Frequency of elevated hCG concentrations (above reference cutoffs) was highest in GTD (100%), followed by GCT (55% to 57%), and other malignancies (8% to 23%). Overall, the Roche cobas Total detected elevated hCG in the greatest number of specimens (63/150). Detection of elevated hCG in trophoblastic disease was nearly equivalent among all immunoassays (range, 41 to 42/60). CONCLUSIONS: While no immunoassay is likely to be perfect in all clinical situations, results for the 5 hCG immunoassays evaluated suggest that all are adequate for use of hCG as a tumor marker in gestational trophoblastic disease and select germ cell tumors. Further harmonization of hCG methods is needed as serial testing for biochemical tumor monitoring must still be performed using a single method. Additional studies are needed to assess the utility of quantitative hCG as a tumor marker in other malignant disease.