SSTR2 and neoplasm: As regards the residence time τ in tumor lesions and in healthy/critical organs, however, a significant difference has been documented which, with the same clearance times and in the presence of the same isotope and the same chelating molecule, is imputable—as expected—to the different receptor affinity that the two distinct somatostatin analogues (TOC and TATE) have for SST-R2.