The cut-off values for soluble CD44, CD44v6, CD44v8-10 and EpCAM suitable for the discrimination between recurrence and non-recurrence in the patients with early stage CCA were 0.505 (area under curve; AUC = 0.670, p = 0.029), 0.814 (AUC = 0.670, p = 0.029), 0.713 (AUC = 0.702, p = 0.010), and 0.506 (AUC = 0.739, p = 0.002), respectively (Additional file 2: Fig. S1). Here, CD44 is linked to cholangiocarcinoma.