Early stage colon cancer patients undergo surgery to remove the tumour as a curative procedure. However, relapse of metastatic or recurrent disease is still observed in a significant proportion of these patients within five years of surgery. Disseminated colon cancer stem cells (CSC), are thought to be responsible for the relapse due to their metastatic ability. The aims are (1) to establish a stem cell culture system (2) to determine CSC biomarkers via RT-PCR differential expression of colon stem cell related genes between stem cells spheres and differeniated organoids (3) to use these markers to detect CSC in healthy blood seeded with colon cancer cells (SW620) and in blood from Stage IV colorectal cancer patients. SW620 cells were plated into ultra low attachment wells in stem cell media (serum-free media plus epidermal growth factor and basic fibroblast growth factor) and complete media. SW620 cells plated in stem cell media grew into distinct spheres within day 4 of culture while SW620 cells plated in complete media grew into differentiated crypt like structures within day 10 of culture. Stem cell spheres serially passaged into single cells, formed spheres within day 6 of culture. RT-PCR was performed using Lgr5, CD133 and EphB2 on day 10 and day 20, spheres and differentiated organoids. Over-expression was observed with Lgr5 (P=0.001) and CD133 (P=0.01) in spheres relative to differentiated organoids. These markers will be used to detect colon CSC in blood. The detection of circulating CSC will yield prognostic information for early stage colorectal cancer patients.