Long Term Efficacy and Assessment of Tumor Response of Transarterial Chemoembolization in Neuroendocrine Liver Metastases: A 15-Year Monocentric Experience

SIMPLE SUMMARY: Neuroendocrine tumors (NET) are rare tumors, with long-term survival even for patients with liver metastases. Transarterial chemoembolization (TACE) is one of the most widely used treatments in this setting. The aim of the study was to assess the long-term efficacy of TACE in a large cohort of patients with NET liver metastases and to correlate imaging findings with survival. In our study including 202 patients with NET liver metastases and a mean follow-up of 8.2 years, TACE was effective to provide disease control for 26 months and a 5.3-year median overall survival (OS). Imaging responses using RECIST and mRECIST criteria were significantly correlated to OS: the median-OS was twice as long among mRECIST responders versus non-responders, with 80.5 months and 39.6 months respectively. These findings are of major importance for everyday practice as they confirm TACE’s effectiveness and usefulness of imaging evaluation to better tailor patient treatment and repeat TACE sessions whenever necessary. ABSTRACT: Background: transarterial chemoembolization (TACE) is an established treatment for neuroendocrine tumor (NET) liver metastases. The aim was to evaluate the long-term treatment efficacy of TACE for NET liver metastases, and correlate imaging response with survival. Methods: this IRB-approved, single-center, retrospective study evaluated all TACE procedures performed for NET liver metastases from 2003–2017 for imaging tumor response (RECIST and mRECIST), time to liver progression (TT(L)P), time to untreatable progression with TACE (TTUP), and overall survival (OS). Patient, tumor, and treatment characteristics were analyzed as prognostic factors. Survival curves according to the Kaplan–Meier method were compared by Log-rank test. Tumor responses according to RECIST and mRECIST were correlated with OS. Results: 555 TACE procedures were performed in 202 NET patients (38% grade 1, 60% grade 2) with primary tumors originating from pancreas, small bowel, and lung (39, 26, and 22% respectively). Median follow-up was 8.2 years (90–139 months). Median TT(L)P and TTUP were 19.3 months (95%CI 16.3–22.3) and 26.2 months (95%CI 22.3–33.1), respectively. Median OS was 5.3 years (95%CI 4.2–6.7), and was higher among mRECIST responders (80.5 months; 95%CI 64.6–89.8) than in non-responders (39.6 months; 95%CI = 32.8–60.2; p < 0.001). In multivariable analysis, age, tumor grade and liver involvement predicted worse OS, whereas administration of somatostatin analogs correlated with improved OS. Conclusion: TACE for NET liver metastases provides objective response and sustained local disease control rates. RECIST and mRECIST responses correlate with OS.