Two studies14, 32 were excluded from the meta-analysis of CD133 and the sub-analysis showed a tendentially significant association between high CD133 expression in tumoral tissue and a poorer prognosis in patients affected by esophageal cancer (HR 1.61; 95%CI 0.99-2.62; I2 59%; p=0.05) (Figure 3B). This evidence concerns the gene PROM1 and esophageal cancer.