EPCAM and Merkel cell skin cancer: One study correlated the presence of miR-375 in serum of patients with MCC23, some others determined T antigen antibodies as a prognostic marker in MCC24,25 and only three studies have investigated CTC detection in MCC: two based on EpCAM-positive selection of CTCs using the CellSearch system and one using the Maintrac system26–28.