Initial Treatment of Unresectable Neuroendocrine Tumor Liver Metastases with Transarterial Chemoembolization using Streptozotocin: A 20-Year Experience.

Background: The majority of patients with neuroendocrine tumor liver metastases (NELM) present with multifocal disease and are not surgical candidates. We present our 20-year experience with transarterial chemoembolization (TACE) using streptozotocin (STZ) in patients with initially unresectable NELM.

Methods: Patients with unresectable NELM treated with TACE using STZ at a single institution from 1995 to 2015 were identified after institutional board approval. Imaging was independently reviewed by a radiologist to evaluate for RECIST 1.1 responses.

Results: Ninety-one patients with NELM who underwent 474 TACE treatments during the past 20 years were identified. Median age was 62 years, and 54 % of the patients were females. Median number of TACE treatments per patient was four (range 1-22). TACE treatment with STZ was very well tolerated with 10.3 % of treatments being associated with side effects, predominantly transient, including hyper/hypotension, bradycardia, or postembolization syndrome. Median overall survival from the start of TACE was 44 months (5-year OS from TACE 40.8 % and 5-year PFS 20.3 %), and 54 % of the patients who had carcinoid syndrome reported improved symptoms after TACE treatments. Age, grade, liver tumor burden, and ability to undergo multiple TACE treatments were independent predictors of overall survival in multivariable analysis. Chromogranin A levels >115 ng/ml were associated with worse overall survival (p < 0.001).

Conclusions: In patients with unresectable NELM, TACE with STZ is well tolerated with minimal toxicity and can lead to diminished carcinoid syndrome and long-term survival. This is a novel, conservative approach for the initial treatment of unresectable NELM.