The invention is in the field of medicine. More specifically, it is in the field of diagnosing tumor angiogenesis status and in the field of medical treatment of a subject who is suffering, suspected to suffer, or might suffer from a tumor in the future. In particular, the invention relates to a fusion polypeptide comprising a foreign antigen and a self antigen, wherein said foreign antigen consists of a polypeptide comprising an amino acid sequence of at least 12-15 amino acid residues, 12-24% of which residues are hydrophilic, bulky amino acid residues selected from the group consisting of histidine, glutamate, arginine, glutamine, aspartic acid and/or lysine.