Nonspecific cross-reacting antigen-50/90 (NCA-50/90) as a new tumor marker

Background The nonspecific cross-reacting antigen-50/90 (NCA-50/90) is a gl ycoprotein antigen which shares some antigenic determinants with carcinoemb ryonic antigen (CEA). No definite clinical value has been established for t he measurement of NCA-50/90 in cancer patients. Methods: I We established a nd evaluated a chemiluminescent enzyme immunoassay (CLEIA) specific for NCA -50/90 using two monoclonal antibodies. Results: No significant reactivity with 4 purified related antigens including CEA uns found in the NCA-50/90 C LEIA. Serum samples (n=572) from patients with malignant (n=326) as well as from healthy individuals (n=246) were analyzed by the NCA-50/90 CLEIA and by the established ACCESS CEA assay. The average sensitivity of NCA-50/90 f or malignant disease was 40.8%, compared to 45.4% of CEA. Relatively high p ositive rates of NCA-50/90 were observed in san from patients with lung can cer (72.0%), hepatoma (62.5%), pancreatic cancer (47.6%), breast cancer (35 .6%), and colorectal cancer (34.5%). About 15% of patients with malignant d isease were positive only for NCA-50/90. The levels of NCA-50/90 and CEA in san from patients with malignant disease correlated only poorly. Conclusio ns: The present study suggests that increases in blood levels of NCA-50/90 occur in a population of cancer patients which is differ ent from those wit h elevated levels of CEA and that NCA-50/90 might be useful for NCA-50/90-p ositive, but CEA-negative patients.