FCN2 and cholangiocarcinoma: Some candidates (including FCN2, ITIH4 and FIBG) also showed higher diagnostic values for early stage CCA (stages I-II) versus PSC than CA19-9 (AUC 0.956, 0.881 and 0.881, respectively), showing the potential usefulness of these serum EV proteomic signatures, as early diagnostic tools in CCA.