Joint EANM, IAEA, and SNMMI practical guidance on somatostatin receptor-targeted radionuclide therapy of neuroendocrine tumours

Somatostatin analogue-based Peptide Receptor Radionuclide Therapy (PRRT) is a molecularly targeted radiopharmaceutical therapy involving the systemic administration of a radiolabelled octreotide derivative designed to target somatostatin receptors (SST) overexpressed on neuroendocrine tumour (NET) cells. PRRT employing radiolabeled somatostatin receptor agonists [ 177 Lu]Lu-DOTATATE, [ 177 Lu]Lu-DOTATOC and [ 90 Y]Y-DOTATOC has been successfully used for the past 25 years in metastatic or locally advanced inoperable NET. PRRT increases progression-free survival, tumour control, and improvement of most patients' NET-associated functional symptoms and quality of life. Side effects are usually mild to moderate and can be acute/subacute or chronic. The former typically include nausea and fatigue in the immediacy of the administration and subacute transient marrow toxicity, both usually mild to moderate. Chronic effects may involve the kidneys, with renal function impairment typically mainly after 90 Y-labelled peptides, and the bone marrow, with the rare occurrence (2-6%) of persistent cytopenias or myelodysplastic diseases. EANM, IAEA, and SNNMI formulated the guidance based on recent literature and experts' opinions. It covers the rationale, indications, and contraindications for PRRT, assessment of treatment response, and patient follow-up. This document aims to guide nuclear medicine specialists in selecting likely candidates to receive PRRT and delivering the treatment safely and effectively.