Endocrine Abstracts

Introduction: ¹³¹I-MIBG is a well-established treatment modality for patients with neuroendocrine tumours (NETs). Our centre has now accumulated over 10 years of experience with ¹³¹I-MIBG therapy, with long term data to evaluate effects on disease progress and other long term outcomes following therapy. Bone marrow effects of radionuclide therapy may include prolonged suppression, myelodysplasia or even frank leukaemia. Incidence is thought to be low, but many reported series have limited follow-up.

Aim: To evaluate disease progression, survival and long term sequelae in patients receiving ¹³¹I-MIBG therapy.

Method: Retrospective review of 75 patients who had received ¹³¹I-MIBG therapy. The number of treatments and the cumulative doses were calculated and disease progression, survival and long-term sequelae were reviewed.

Results: The data so far demonstrate stabilisation of disease with ¹³¹I-MIBG therapy in the majority of cases. Some patients were subsequently noted to have haematological pathologies, ranging from myelodysplasia to frank leukaemia. These effects were seen in patients over a wide range of doses received (27 to 47 GBq) and with different sites of disease. In these patients, the haematological disorders occurred at least five years following commencement of ¹³¹I-MIBG therapy. It is relevant to compare ¹³¹I-MIBG outcomes to available long-term data in patients receiving ¹³¹I therapy for thyroid malignancy and for radiolabelled somatostatin analogues for neuroendocrine tumours.

Conclusion: With effective 131I-MIBG therapy, patients with NETs are surviving longer and sequelae may become apparent. A detailed review of the long-term outcomes in patients receiving radionuclide therapies would be timely, in order to evaluate long term risks and benefits. Long term 131I-MIBG follow up data would be a useful comparator against other newer radionuclide therapies in use or in current trials and would provide detailed information about additional risk factors and predictors of adverse effects that may influence rational therapy choices.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.