POU5F1 and cholangiocarcinoma: Moreover, OCT4+CTC (versus none CTC) (HR = 5.992, P = 0.002), previous chemotherapy (no) (HR = 3.869, P = 0.001), and treatment line of second or above (versus first) (HR = 3.869, P = 0.001) were correlated with poorer OS in advanced CCA patients (Fig. 5A).