Aim
Grade 3 NENs are aggressive tumours with poor prognosis. PRRT +/- radiosensitising chemotherapy is a potential treatment for disease with high SSTR-expression without spatially discordant FDG-avid disease. We retrospectively evaluated the efficacy of PRRT in G3 NEN.
Materials & Methods
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All patients with G3 NEN (Ki-67>20% on immunohistochemistry) and who had completed at least one cycle of PRRT between January 2005 and January 2017 were retrospectively reviewed. Kaplan-Meier estimate was used to determine progression free survival (PFS) and overall survival (OS) defined from start of PRRT. Subgroup analysis was performed for patients with Ki-67≤55% and >55%. Anatomical response (CT RECIST 1.1) and toxicity 3 months after PRRT was determined. Disease control rate (DCR) was defined as complete response (CR), partial response (PR) and stable disease (SD) of those with prior progression. |
Results
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28 patients (M=17; age 16-78 y.o; Ki-67≤55%=22) were reviewed. 17 patients had pancreatic, 5 small bowel, 3 large bowel, 2 bronchial and 1 unknown primary disease. 25/28 had significant FDG-avid disease prior to treatment. Most had 177Lu-DOTA-octreotate (median cumulative activity 24.4 GBq, median 4 cycles). 20 had radiosensitising chemotherapy. 89% were treated for disease progression; 79% after prior chemotherapy. Median follow-up was 29 months. The median PFS was 9 months for all patients. 16 patients died (Ki-67≤55%=11; Ki-67>55%=5) with median OS of 19 months. For Ki-67≤55% (N=22), the median PFS was 12 months and median OS 46 months. For Ki-67>55% (N=6), the median PFS was 4 months and median OS 7 months. On CT imaging, DCR at 3 months post PRRT was 74%; 35%(8/23) PR and 39% (9/23) SD. Grade 3 and 4 thrombocytopenia occurred in five patients. No renal or liver toxicity related to treatment was seen. |
Conclusion
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PRRT achieves clinically-relevant disease control with acceptable toxicity in G3 NENs. |