The Impact of Extent of Liver Resection Among Patients with Neuroendocrine Liver Metastasis: an International Multi-institutional Study

Background: Liver resection in patients with neuroendocrine liver metastasis (NELM) provides a survival benefit, yet the optimal extent of resection remains unknown. We sought to examine outcomes of patients undergoing non-anatomic (NAR) versus anatomic liver resection (AR) for NELM using a large international cohort of patients. Methods: Two hundred and fifty-eight patients who underwent curative intent liver resection from January 1990 to December 2016 were identified from eight institutions. Patients were excluded if they underwent concurrent ablation, had extrahepatic disease, underwent a debulking operation, or had mixed anatomic and non-anatomic resections. Overall (OS) and recurrence-free (RFS) survival were compared among patients based on the extent of liver resection (AR vs. NAR). Results: Most primary tumors were located in the pancreas (n = 117, 45.4%) or the small intestine (n = 65, 25.2%). Liver resection consisted of NAR (n = 126, 48.8%) or AR (n = 132, 51.2%) resection. The overwhelming majority of patients who underwent NAR had an estimated liver involvement of < 50% (NAR 109, 97.3% vs. AR n = 82, 65.6%; P < 0.001). Patients who underwent NAR also had higher rates of primary tumor lymph node metastasis (NAR n = 79, 71.2% vs. AR n = 37, 33.6%; P < 0.001) and microscopically positive margins (R1) (NAR n = 29, 25.7% vs. AR n = 16, 12.5%; P = 0.009). After a median follow-up of 47.7 months, 48 (18.6%) patients died and 37.0% (n = 95) had evidence of disease recurrence. Patients who underwent AR had both longer median OS (not reached) and RFS (not reached) versus patients who underwent NAR (median OS 138.3 months; median RFS 31.3 months) (both P < 0.01). After controlling for patient and disease-related factors, extent of liver resection was independently associated with an increased risk of recurrence (HR 2.39, 95% CI 1.04–5.48; P = 0.04) but not death (HR 1.92, 95% CI 0.40–9.28; P = 0.42). Conclusion: NAR was independently associated with a higher incidence of recurrence versus patients who undergo a formal anatomic hepatectomy among patients with NELM.