To Örebro University

Introduction: Above-label doses of long-acting somatostatin analogues (SSAs) are increasingly used for the control of secretory syndrome or as anti-proliferative treatment in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs).

Aim(s): The aim of this study was to evaluate the anti-proliferative effect of increased dose of SSAs in patients with GEP-NETs.

Materials and methods: We collected retrospectively the data of patients with GEP-NETs that received SSAs every 3 or 2 weeks, after disease progression on standard 4-weekly doses. We analysed clinical, biochemical and radiographic response data and identified factors that may influence the outcome.

Results: We analysed the data of 16 patients. 7 patients suffered from pancreatic NET (pNET) and 9 from small intestinal NET (si-NET). Indications for dose increase were radiographic progression (62,5%), increasing biomarkers (12,5%) or inadequate syndrome control (25%). Among patients with radiographic progression before the escalation of SSA dose, 3 had disease stabilization and 7 eventually progressed radiographically. Median PFSwas 36 months. PNETs were associated with a significantly lower PFS compared to si-NETs (P= 0.041). Patients with NET with a Ki-67 labelling index≤5 displayed a significantly higher PFS (P= 0.047). No significant difference was observed between patients who received above-label SSAs due to clinical/biochemical or radiographic response (P=0.1). In univariate analysis, the Ki-67≤5 was marginally associated with significantly longer PFS (P=0.05).

Conclusion: The administration of above-label doses of SSAs maybe a valuable option in patients who progress on the standard 4-weekly regimen, especially in patients with si-NETs or a Ki-67 labelling index≤5.