Almost 40 years ago, researchers found out that the Thomsen-Friedenreich (TF) and the Thomsen nouvelle (Tn) antigens could be detected in carcinoma, but not in healthy tissue. A short time after that it became clear that TF and Tn are precursor molecules of the MN-blood group antigens. In normal tissue TF and Tn are coated by glycosyl structures, thereby forming the glycoproteins which are known to account for the MN-blood group, but in malignant tissue these molecules are uncovered.TF, which has an additional Galectin-residue compared to Tn, is correlated with a more favourable prognosis for patients. On the contrary, patients with Tn-bearing tissues have a worse prognosis for overall and progression-free survival. It is known that TF and Tn are involved in the adhesion of tumour cells to the endothelium via a mechanism recruiting Galectin-3 and MUC-1, which is the first step in metastasis formation. Furthermore, it became clear that this pathway can be blocked by a growing number of molecules, thereby creating ways of therapeutical intervention.