For elevated serum levels of the soluble extracellular domain of CD44v6 and the CD44 ICD an association with tumor burden, metastasis and poor prognosis in several cancers including gastric, colorectal or breast cancer have been shown (Guo et al., 1994; Sheen-Chen et al., 1999; Yamane et al., 1999; Stamenkovic and Yu, 2009). This evidence concerns the gene CD44 and cancer.