Outcomes of first-line long-acting octreotide treatment in non-functional, advanced gastroenteropancreatic neuroendocrine tumors.

Purpose: Benefits of somatostatin analogues have been mostly studied in mixed samples of patients including both functional and non-functional neuroendocrine tumors. This study aimed to examine the response of patients with non-functional metastatic or inoperable gastroenteropancreatic neuroendocrine tumors (GEP-NETs) that received first-line treatment with the somatostatin analogue octreotide LAR.

Methods: The medical records of 23 patients with locally inoperable or metastatic non-functional neuroendocrine tumors who received octreotide LAR (long acting release) treatment were retrospectively reviewed for clinical data and disease course. All patients had received first-line octreotide LAR 30 mg for 4 weeks. Progression free survival (PFS) and overall survival (OS) were the primary and secondary endpoints, respectively.

Results: All patients were followed for a median of 47 months. Mean PFS and OS were 25.0 ± 3.4 months (95% CI: 18.4-31.5) and 71.3 ± 9.5 months (95% CI: 52.7-89.9), respectively, with an estimated 5-year OS of 58%. Patients with ≤ 25% of hepatic tumor load had better PFS when compared to patients with >25% hepatic tumor load (32.2 ± 6.2 vs 19.4 ± 2.7 months, p=0.043). During treatment, the following adverse events developed: skin reaction (N=1, 4.3%), cholestasis (N=1, 4.3%), grade 1 diarrhea (N=1, 4.3%), and newly onset diabetes (N=3; 13.0%).

Conclusion: Octreotide LAR seems to be an effective treatment option with acceptable tolerability for patients with well-differentiated non-functional GEP-NETs. Survival benefits warrant further testing in future large-scale prospective trials.