Blood samples will be used as per the study protocol. Consented subjects will provide at least 10 ml but not more than 20 ml (for repeating testing) of blood at each time point for Epi proColon testing. An additional volume of up to 10 ml anticoagulated blood will be drawn for circulating colonic epithelial cell analysis at each time point. Blood samples will be stored and will only be used in future research with the express written permission of study subjects. Subjects may withdraw consent from the study or for future use of blood samples at any time.