Cancer research is the intense scientific effort to understand disease processes and discover possible therapies. While understanding of cancer has greatly increased since the last decades of the 20th century, radically new therapies are only discovered and introduced gradually.

Targeted therapy which first became available in the late 1990s has had a significant impact in the treatment of some types of cancer, and is currently a very active research area. This constitutes the use of agents specific for the deregulated proteins of cancer cells. Small molecules (such as the tyrosine kinase inhibitors imatinib and gefitinib) and monoclonal antibodies have proven to be a major step in oncological treatment. Targeted therapy can also involve small peptidic structures as ´homing device´ which can bind to cell surface receptors or affected extracellular matrix surrounding the tumor. Radionuclides which are attached to this peptides (e.g. RGDs) eventually kill the cancer cell if the nuclide decays in the vicinity of the cell (vide supra Radiation therapy). Especially oligo- or multimeris of these binding motifs are of great interest, since this can lead to enhanced tumor specificity and avidity.