Endocrine Abstracts

Background: Neuroendocrine tumours (NETs) represent a diverse group of neoplasms arising from neuroendocrine cells. Streptozotocin (STZ) based chemotherapy regimens have been utilized in the treatment of NETs, yet comprehensive clinical outcomes remain to be fully elucidated.

Methods: We retrospectively analyzed median overall (mOS) & progression-free survival (mPFS) among 26 patients with pancreatic and non-pancreatic NETs and NECs treated with STZ-based chemotherapy from July 2014 at Nottingham University Hospitals. Data were identified from Multi-disciplinary Team health records and analyzed using SPSS Statistics, v28.0. Survival analysis utilized Kaplan-Meier curves for cumulative survival estimates, with the Log rank test for comparing rates.

Results: We included 26 patients (53.8% males; median age: 65). Out of 26 patients: 3 had Streptozocin/5 fluorouracil; 3 had Streptozocin/5 fluorouracil/Cisplatin and 20 had Streptozocin/5 fluorouracil/Carboplatin regimen. Median overall survival (OS) was 12.63 months (95% CI 7.5-17.6), & median progression-free survival (PFS) was 5.07 months (95% CI 1.66 – 8.47). No significant differences were found between pancreatic and non-pancreatic NETs, metastatic sites, functional status, or chemotherapy regimen. Statistically significant differences were found in survival outcomes between tumors positive and negative for octreotide receptor expression (mOS: 21.7 vs 4.6 months, P = 0.05) and Ki-67 expression levels (≤50% Vs >50%) (mOS: 19.96 vs 4.8 months, P = 0.031). Patients receiving >5 treatment cycles had better survival compared to <5 cycles (median OS: 33.3 vs 12.34 months, P = 0.002). Response rates at 3, 6, 9, and 12 months were 61.5%, 46.2%, 30.8%, and 26.9% respectively. 50% patients had STZ dose reduction, with no significant impact on survival. 7.7% discontinued STZ due to toxicity; G3 toxicities were Fatigue (7.7%) & Neutropenia (3.8%).

Conclusions: Our study although limited by size underscores the prognostic significance of biomarkers such as Ki-67 index and octreotide receptor expression, as well as the number of treatment cycles in managing neuroendocrine tumors. While consistent with phase 3 trial results, larger-scale controlled studies are warranted to better understand treatment regimen effects on clinical outcomes in NET management.