Long-term survival and toxicity in patients with progressive advanced neuroendocrine tumors treated with lutetium peptide radiolabelled radiotherapy: A Western Australian long-term follow-up study.

Abstract

e16202 Background: There are limited treatment options for advanced neuroendocrine tumours, and radiolabelled somatostatin analogues have shown favourable safety and efficacy over other existing treatments. Lutetium Octreotate has been shown to be the somatostatin analogue of choice in Peptide Radiolabelled Radiotherapy (PRRT) for advanced neuroendocrine tumours (NETs). Methods: We conducted a retrospective review of the long term safety and survival outcomes of 104 patients prospectively treated on the CLEMENT1, CLEMENT2, NETTLE, and NETT VALuE trials where patients with advanced progressive NETs were treated with Lutetium Octreotate PRRT in Perth, Western Australia. With a median follow-up time of 68 months, this is the longest follow-up study of advanced NETs treated with Lutetium PRRT in the literature to date. Results: Results showed comparable periods of disease stability as other studies, with median progression free survival of 43 months, and superior survival to other series, with a median survival of 71 months. There were patients who had very durable responses, with five year overall survival 61.5%, five year progression free survival 30.1%, 10 year overall survival 30.1%, and 10 year progression free survival of 29.3%, demonstrating Lu 177 can provide a very long duration of response in some patients. PRRT treatment was well tolerated with 1.9% of patients suffering long term renal impairment, and 1% with long term mild thrombocytopenia attributed to PRRT. Importantly, there was a higher rate of MDS and leukaemia in our series (6.7%), which is likely attributed to the longer period of follow-up with all except one case occurring 48 months after PRRT treatment, which is later than the median follow up in most other studies. Conclusions: Overall, this study showed that Lutetium PRRT remains an efficacious and well tolerated treatment in long term follow-up. For clinicians deciding on the timing of PRRT for individual patients the 6.7% long term risk of MDS/leukaemia needs to be balanced against the 29.3% PFS at 10 years. Clinical trial information: ACTRN12610000440022.