A limiting factor for the progress of radionuclide-based cancer diagnostics and therapy--availability of suitable radionuclides.

Advances in diagnostics and targeted radionuclide therapy of haematological and neuroendocrine tumours have raised hope for improved radionuclide therapy of other forms of disseminated tumours. New molecular target structures are characterized and this stimulates the efforts to develop new radiolabelled targeting agents. There is also improved understanding of factors of importance for choice of appropriate radionuclides. The choice is determined by physical, chemical, biological, and economic factors, such as a character of emitted radiation, physical half-life, labelling chemistry, chemical stability of the label, intracellular retention time, and fate of radiocatabolites and availability of the radionuclide. There is actually limited availability of suitable radionuclides and this is a limiting factor for further progress in the field and this is the focus in this article. The probably most promising therapeutic radionuclide, 211At, requires regional production and distribution centres with dedicated cyclotrons. Such centres are, with a few exceptions in the world, lacking today. They can be designed to also produce beta- and Augeremitters of therapeutic interest. Furthermore, emerging satellite PET scanners will in the near future demand long-lived positron emitters for diagnostics with macromolecular radiopharmaceuticals, and these can also be produced at such centres. To secure continued development and to meet the foreseen requirements for radionuclide availability from the medical community it is necessary to establish specialized cyclotron centres for radionuclide production.