The search continues to find methods to more effectively distinguish colorectal carcinoma patients who could be separated into high-risk and low-risk categories. Investigators have reported on the detection of occult micrometastases in bone marrow using antibodies to cytokeratin, which is a marker of epithelial cells but which has no tissue specificity, as opposed to villin, a cytoskeletal protein that is specifically involved in the formation of brush-border microvilli in the small intestine and colon epithelium.Specificity and sensitivity of antibody to villin (ID2C3) and antibody to cytokeratin (A45-B/B3) were first studied in normal bone marrow and in a test system in which cancer cell lines were mixed in normal bone marrow. In a preliminary study including 16 colorectal carcinoma patients, we compared the number of villin-positive cells with cytokeratin-presenting cells.As A45