CD133 expression as a prognostic marker has been found in colorectal cancer [11-18] and brain tumours [19-21] but it is still unclear if CD133 can be used as a prognostic marker in pancreatic cancer [22], ovarian cancer [23], hepatocellular cancer [24,25] and non-small cell lung carcinoma [26]. This evidence concerns the gene PROM1 and ovarian cancer.