Peptide Receptor Radionuclide Therapy of Neuroendocrine Tumors: how important is internal dosimetry?

We are grateful to Mr Trauernicht and Dr du Toit for their letter to the editor written on the recently published South African practice guidelines on peptide radionuclide therapy of neuroendocrine tumors.1 In the letter, they express concern that internal dosimetry was discussed in "only a single short paragraph" and that this may create an impression that "internal dosimetry assessment is just an optional extra." The authors drew a contrast between the South African guidelines and the joint International Atomic Energy Agency (IAEA), European Association of Nuclear Medicine (EANM) and the Society of Nuclear Medicine and Molecular Imaging guidelines published earlier where "a whole section on dosimetry" was included.2 The NETTER-1 trial is a phase III trial that demonstrated the superiority (regarding survival benefits) of peptide receptor radionuclide therapy (PRRT) of well-differentiated metastatic midgut neuroendocrine tumours (NETs) using Lu-177 DOTATATE over long-acting octreotide alone.3 Following the report of this trial, many regulatory authorities around the world approved the use of this radionuclide therapy option in routine clinical practice. Consequently, the demand by patients and their oncologists for this highly effective therapy with tolerable side effects increased tremendously in South Africa and elsewhere around the world. In response to this high demand, the College of Nuclear Physicians (CNP) of South Africa, on behalf of the South African Society of Nuclear Medicine (SASNM), came together to publish practice guidelines to "assist Nuclear Medicine Physicians in the evaluation, safe administration and follow-up (assessment of response and long-term toxicities) of patients with NETs referred for or considered for PRRT". (authors)