Liver embolisation for patients diagnosed with neuroendocrine neoplasms: Systematic review and meta-analysis of the literature

Background: Liver embolisation is one of the treatment options available for patients diagnosed with neuro-endocrine neoplasms (NEN), especially in the presence of carcinoid syndrome. It is still uncertain whether the benefits of the various types of embolisation treatments truly outweigh the complications in NENs. This systematic review assesses the available data relating to liver embolisation in patients with NENs.

Methods: Eligible studies (identified using MEDLINE-PubMed) were those reporting data on NEN patients (any grade) who had undergone any type of liver embolisation. The primary end points were best radiological response and symptomatic response; secondary end-points included progression-free survival (PFS), overall-survival (OS) and toxicity. Weighted pooled proportions and means with 95% confidence intervals (95% CI) were calculated, weighted according to the number of patients included (analytical weighting).

Results: Of 598 studies screened, 101 were eligible: 56 studies were retrospective (55.5%), whilst 15 were prospective (14.9%). The eligible studies included a total of 5545 NEN patients, with a median of 39 patients per study (range 5–214). Most studies reported data on trans-arterial chemoembolisation (TACE) (46.5%) followed by trans-arterial bland embolisation (TAE) (20.7%) and radioembolisation (RE) (19.8%). Pooled partial response rate was 36.6% (28.9% achieved stable disease) and 55.2% of patients had a symptomatic response to therapy. The median PFS and OS were 18.4 months (95% CI 15.5–21.2) and 40.7 months (95% CI 35.2–46.2), respectively. The most common toxicities were found to be abdominal pain (48.8%) and nausea (46.1%). Outcome did not significantly vary depending on the type of embolisation performed: partial response (50.7% with TAE, 33.5% with TACE, 42.4% for RE); PFS at (22.1 months with TAE, 19.2 months with TACE; 12.6 with RE).

Conclusion: Liver embolisation provides adequate symptom relief and radiological response in a significant number of patients, with favourable PFS. The use of TACE and RE do not seem to significantly improve patient outcomes over TAE. Quality of studies was limited, highlighting the need of further prospective, randomised phase III studies to confirm the most suitable form of liver embolisation in NENs.