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 glycoprotein antigen which shares some antigenic determinants with carcinoembryonic antigen (CEA). No definite clinical value has been established for the measurement of NCA-50/90 in cancer patients.

METHODS

We established and 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 was found in the NCA-50/90 CLEIA. 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 for malignant disease was 40.8%, compared to 45.4% of CEA. Relatively high positive rates of NCA-50/90 were observed in sera from patients with lung cancer (72.0%), hepatoma (62.5%), pancreatic cancer (47.6%), breast cancer (35.6%), and colorectal cancer (34.5%). About 15% of patients with malignant disease were positive only for NCA-50/90. The levels of NCA-50/90 and CEA in sera from patients with malignant disease correlated only poorly.

CONCLUSIONS

The present study suggests that increases in blood levels of NCA-50/90 occur in a population of cancer patients which is different from those with elevated levels of CEA and that NCA-50/90 might be useful for NCA-50/90-positive, but CEA-negative patients.