A binding structure which binds in, and/or to the surface of, tumour cells; a target structure displayed and/or expressed in, or on the surface of, tumour cells; a binding structure that recognises and blocks said target structure; a substance that binds to or blocks the expression of said target structure; pharmaceutical compositions comprising said binding structure, target structures or substance as active principles; vaccine compositions comprising said target structures as active principles; a method for phage selection; and methods of in vitro and in vivo diagnosis and prognosis, and of treatment of human malignant diseases comprising the use of the above subject matters, are described.