Abstract
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Objectives Metastasized neuroendocrine tumors of the stomach (G-NET) are rare and no approved sytemic therapeutic options are available. The aim of this retrospective study was to assess the efficacy of peptide receptor radionuclide therapy (PRRT) as first or second line treatment option in advanced metastatic G-NET.
Methods In our database we found 6 patients with metastasized and progressive G-NET who were evaluated for PRRT using Y-90 or Lu-177 DOTATATE. Five of these patients were finally treated with PRRT. Three of these patients were treated in our hospital, the other two patients outside. Response assessment (using RECIST) was performed at 3 months after the last cycle by using Ga-68 DOTATATE PET/3-Phase ceCT, MRI and esophagogastroduodenoscopy (EGD). PRRT was performed under appropriate amino acid nephroprotection. Kidney function assessment of the patients treated at our institute was performed using Tc-99m MAG3 dynamic scintigraphy.
Results PRRT was performed in 1-4 cycles; dose range for Y-90 DOTATATE 2.1 - 4.6 GBq, for Lu-177 DOTATATE 5.3 -7.5 GBq. The primary tumor could be resected in one patient after completion of the PRRT. One patient received PRRT after partial gastrectomy. Overall, 4/5 patients received PRRT as first line therapy. Response assessment at 3 months after the end of PRRT showed partial remission in 2 patients, stable disease in 1 patients, and minor or partial response in two patients. PRRT successfully achieved its aim of reducing the primary tumor in size in 1patient (partial remission on EGD). One patient showed grade 3 hematotoxicity and grade 3 nephrotoxicity. The remaining 4 patients showed no appreciable PRRT related toxicity.
Conclusions To the best of our knowledge this study shows for the first time that PRRT is a good first or second line treatment option in patients with advanced metastatic progressive gastric NET