CD93 and colorectal carcinoma: The low CD93 levels could indicate that only a small amount of CD93 is released from the tumour into the circulating blood of CRC patients due to unknown mechanisms or that the patients have an immunologic imbalance resulting in impaired production of CD93 from leucocyte and endothelial cells and/or restricts the secretion of CD93 from epithelial cells in colon and rectum.