In this regard, the sodium iodide symporter (NIS) represents an advantageous and highly efficient target gene, as functional NIS gene expression allows exact localization of the tumorous tissue by administration of NIS specific tracers such as 123I, 124I and the novel NIS positron-emissions-tomography (PET) tracer 18F-tetrafluoroborate (18F-TFB) and at the same time gives the possibility of cytotoxic radioiodide treatment. This evidence concerns the gene SLC5A5 and neoplasm.