Prior Resection Of The Primary Tumor Prolongs Survival After Peptide Receptor Radionuclide Therapy Of Advanced Neuroendocrine Neoplasms

Objective: The aim of the study was to compare impact on survival after resection of primary tumors (PTs) after peptide receptor radionuclide therapy (PRRT).Background: PRRT is a highly effective therapeutic option to treat locally advanced or metastatic neuroendocrine neoplasms (NENs).Methods: We retrospectively analyzed the data of 889 patients with advanced NEN (G1-G3, stage IV) treated with at least 1 cycle of PRRT. In 486 of 889 patients (55%, group 1), PT had been removed before PRRT. Group 2 constituted 403 patients (45%) with no prior PT resection. Progression-free survival (PFS) and overall survival (OS) was determined by Ga-68 SSTR-PET/ CT in all patients applying RECIST and EORTC.Results: Most patients had their PT in pancreas (n = 335; 38%) and small intestine (n = 284; 32%). Both groups received a mean of 4 cycles of PRRT (P = 0.835) with a mean cumulative administered radioactivity of 21.6 +/- 11.7 versus 22.2 +/- 11.2 GBq (P = 0.407). Median OS in group 1 was 134.0 months [confidence interval (CI): 118-147], whereas OS in group 2 was 67.0 months (CI: 60-80; hazard ratio 2.79); P < 0.001. Likewise, the median progression-free survival after first PRRT was longer in group 1 with 18.0 (CI: 15-20) months as compared to group 2 with 14.0 (CI: 15-18; hazard ratio 1.21) months; P = 0.012.Conclusions: A previous resection of the PT before PRRT provides a significant survival benefit in patients with NENs stage IV.