Application of cancer procoagulant as an early detection tumor marker.

BACKGROUND: In spite of many advances in the analytical reagents (antibodies), analytical systems, and the clinical application of tumor markers, the present markers do not detect early stage cancer. Preliminary data with an antigen specific to tumor tissue, cancer procoagulant (CP), suggest its possible role in the detection of early stage cancer. This study was aimed at determining the clinical use of CP as an early stage tumor marker. METHODS: An improved enzyme-linked immunosorbent assay (ELISA) was developed to measure CP concentration in serum. A panel of 817 blinded serum samples were examined from three groups of people: 573 cancer, 106 benign, and 139 normal. RESULTS: The sensitivity of all samples analyzed from cancer patients was 80%. The CP ELISA was able to detect ovarian, colon, and kidney cancer at a sensitivity greater than 85%; breast, prostate and small cell lung cancer was detected at a sensitivity of 80-85%. Particularly interesting was the observation that early stage cancers, regardless of site, were detected effectively. In some groups, the CP assay correctly identified 100% of the patients with stage I and II cancer. The assay was able to identify correctly noncancer patient sera at a specificity of 83% for those with benign disease and 82% for the normal individuals. CONCLUSIONS: The CP assay has potential as an aid in diagnosing early stage malignancies and thereby may significantly improve the survival rate of cancer patients.