797

Background: The early detection of colorectal cancer is essential because this cancer can be cured surgically if diagnosed early. We assessed the feasibility of using a new technique for isolating colonocytes from naturally evacuated feces, followed by cytologic or molecular biologic evaluation of the colonocytes to detect colorectal cancer arising in any part of the colorectum. Several simulation studies were conducted to establish optimal techniques for retrieving colonocytes from any portion of feces. Prospective clinical studies showed that the overall sensitivity and specificity were 71% (82 of 116) in patients with colorectal cancer and 88% (73 of 83) in healthy volunteers. However, the cost of the entire procedure is very high. To reduce the cost, we have developed new immuno-magnetic beads and improved their efficiency for retrieving colonocytes from naturally evacuated feces. Methods: Magnetic beads of several sizes (4.2-5.9 μm) were prepared and tagged with antibodies against Ep-CAM. For simulation experiments, the recovery rate of 1 x 104 HT-29 colonic cancer cells was examined using an established method (Matsushita H. et al, Gastroenterol 129:1918-1927, 2005). Results: The recovery rate of HT-29 cells with some of our newly developed immuno-magnetic beads was equivalent to that with Dynabeads Epithelial Enrich (Dynal, Oslo, Norway). Conclusions: We have successfully developed immuno-magnetic beads with Ep-CAM antibodies. To date, the performance of some of the beads is good, as compared with Dynabeads Epithelial Enrich.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA