Neuroendocrine tumours (NETs) are a heterogeneous group of uncommon hormonally active neoplasms that express somatostatin receptors. Peptide receptor radionuclide therapy (PRRT) has been successfully used to treat gastroenteropancreatic neuroendocrine tumours (GEPNET) and other somatostatin receptor expressing tumours for almost 40 years. The first patient treated with PRRT in Australia was in 1996 with 111In-octreotide at the Peter MacCallum Cancer Centre [1].
The mainstay of initial therapy was with Auger electron producing Indium-111 (111In), however it was quickly replaced with the beta particle emitters: initially the long range Yttrium-90 (90Y) and followed by the short range 177Lu-DOTA-Octreotate [1]. The short range beta particle production of Lutitium-177 (177Lu) has made it favourable and now the mainstay of GEPNET treatment for metastatic or unresectable disease [2, 3]. The benefits for an individual patient, including progression free survival and quality of life, are weighed against possible complications of nephrotoxicity and bone marrow toxicity [4].
Targeted alpha therapy is currently an investigational therapy proposed to supersede beta therapy with an even shorter range to avoid collateral non-tumour tissue irradiation. In addition, the higher linear energy transfer (LET) of an alpha is more likely to result in cell death [5]. The following isotopes are under investigation: Actinium-225 (225Ac), Lead-212 (212Pb) and Bismuth-213 (213Bi) [6].
The following presentation will discuss the history of PRRT followed by a review of current and proposed new therapies including alpha therapy, dosimetry following therapy.