Replace the current FOBT (fecal occult-blood tests) used in CRC screening for colorectal cancer in individuals over age 50. We have shown upregulation of TAA mRNA expression in colon tumors. We have produced monoclonal antibodies and affinity purified antisera to the TAA and have used these to formulate a prototype sandwich enzyme immunoassay in a microplate format. We have used this assay to test 70 stool specimens and a number of colonic washes from patients in which a tumor was subsequently found. In a head-to-head comparison with two different fecal occult blood tests (FOBT), the prototype sandwich assay has demonstrated superior clinical diagnostic performance to both. Work has begun on assembling two, 500 specimen panels to demonstrate utility of the marker in relevant populations. Additional Phase I objectives are to 1) generate additional monoclonal antibodies to the TAA; 2) complete cloning and sequencing of the TAA from human tumor specimens. The product we visualize is a low cost, one-step immunoassay device suitable for use in a screening mode in which patients with a positive test result would be worked up by sigmoidoscopy or colonoscopy. PROPOSED COMMERCIAL APPLICATIONS: Replace the current FOBT ( fecal occult-blood tests) used in CRC screening with an immunoassay for a TAA found in stool. A successful product will more than double the number of cancers detected, detect pre-cancerous lesions not currently detected, and cut the number of false-positives by 3 to 5 fold or more.