Identified risk factors provide a limited (<30 %) risk estimate even with target tissue dosimetry. These data strongly suggest the existence of unidentified individual susceptibilities to radiation-associated disease.

Peptide receptor radionuclide therapy (PRRNT) is a molecularly targeted radiation therapy involving the systemic administration of a radiolabelled peptide designed to target with high affinity and specificity receptors overexpressed on tumours. PRRNT employing the radiotagged somatostatin receptor agonists 90Y-DOTATOC ([90Y-DOTA0,Tyr3]-octreotide) or 177Lu-DOTATATE ([177Lu-DOTA0,Tyr3,Thr8]-octreotide or [177Lu-DOTA0,Tyr3]-octreotate) have been successfully used for the past 15 years to target metastatic or inoperable neuroendocrine tumours expressing the somatostatin receptor subtype 2. Accumulated evidence from clinical experience indicates that these tumours can be subjected to a high absorbed dose which leads to partial or complete objective responses in up to 30 % of treated patients. Survival analyses indicate that patients presenting with high tumour receptor expression at study entry and receiving 177Lu-DOTATATE or 90Y-DOTATOC treatment show significantly higher objective responses, leading to longer survival and improved quality of life. Side effects of PRRNT are typically seen in the kidneys and bone marrow. These, however, are usually mild provided adequate protective measures are undertaken. Despite the large body of evidence regarding efficacy and clinical safety, PRRNT is still considered an investigational treatment and its implementation must comply with national legislation, and ethical guidelines concerning human therapeutic investigations. This guidance was formulated based on recent literature and leading experts’ opinions. It covers the rationale, indications and contraindications for PRRNT, assessment of treatment response and patient follow-up. This document is aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRNT and to deliver the treatment in a safe and effective manner. This document is largely based on the book published through a joint international effort under the auspices of the Nuclear Medicine Section of the International Atomic Energy Agency.

(177)Lu-DOTATATE was well tolerated up to 29 GBq cumulative activity (up to 7.4 GBq/cycle). The maximum tolerated dose/cycle was not reached. However, considering the individual bone marrow function and the presence of risk factors for kidney toxicity, it seems safer to divide cumulative activities into lower activity cycles.

Our results indicate the importance of clinical screening for risk factors: In this case, a BED <28 Gy is recommended. Fractionation of therapy is important in order to decrease toxicity, and further studies are needed to evaluate its clinical impact.

The authors were listed in the wrong order, and one of their names was spelt incorrectly. These mistakes are rectified here.The online version of the original article can be found htt://dx