Somatostatin receptor endoradiotherapy of neuroendocrine tumors: experience in Hungarian patients

Beside conventional therapies for the treatment of neuroendocrine tumors, a new therapeutical approach, peptide receptor radionuclide therapy has been developed recently. There are two important features which make this therapy feasible: somatostatin receptors are strongly over-expressed in most neuroendocrine tumors resulting in a high tumor-to-background ratio and internalization of the somatostatin-receptor complex in neuroendocrine cells. Due to these features, neuroendocrine tumors can be treated with radiolabelled somatostatin analogues. For peptide receptor radionuclide therapy, somatostatin analogues are conjugated to a chelator that can bind a radionuclide. The most frequently used radionuclides for neuroendocrine tumor treatment are the β-emitter Yttrium-90 (⁹⁰Y) and the β+γ emitter Lutetium-177 (¹⁷⁷Lu). Candidates for somatostatin receptor endoradiotherapy are patients with progressive, metastatic, somatostatin-receptor positive neuroendocrine tumors. Many patients have been successively treated with this approach: according to international results major remission can be achieved in 25% of the cases. Although this therapy is still unavailable in Hungary, Hungarian patients can be treated with somatostatin receptor endoradiotherapy with financial support from the National Health Fund in a co-operation with the University of Basel since 2005. During the past 5 years, 51 Hungarian patients have been treated with this therapy. This review briefly summarizes the theoretical background, indications, effectiveness and side effects of somatostatin receptor endoradiotherapy and the authors present the first data obtained from Hungarian patients.