Receptor Radionuclide Therapy with 90Y-[DOTA0]-Tyr3-Octreotide (90Y-DOTATOC): The IEO Experience

High concentrations of subtype 2 somatostatin tumor receptors are expressed in numerous tumors, enabling primary and metastatic masses to be localized by scintigraphy after injecting ¹¹¹In-labeled somatostatin analogue octreotide. Receptor radionuclide therapy consists in the intravenous administration ofa peptide, such as octreotide, labelled with a therapeutic radionuclide. The basis for receptor radionuclide therapy with radiolabelled octreotide in somatostatin receptor rich tissues is the receptor-mediated endocytosis of the radiopeptide that is trapped inside the cytoplasm, thus allowing the irradiation of the cell. Dosimetric studies indicate that ⁹⁰Y-[DOTA]⁰-Tyr3-Octreotide (⁹⁰Y-DOTATOC) is suitable for efficient receptor radiotherapy. ⁹⁰Y-DOTATOC therapy has proven to be a safe and effective treatment. Possible toxicity deriving from ⁹⁰Y-DOTATOC therapy may be divided in to acute and delayed. Probably the radius of beta emission of the radioisotope has to fit the tumor dimension. Therefore, the administration of combinations of radioisotopes for different sized lesions should be evaluated in future studies.