Outcomes of Cytoreductive Surgery for Metastatic Low-Grade Neuroendocrine Tumors in the Setting of Extrahepatic Metastases.

Background: Neuroendocrine tumors (NETs) have a uniquely indolent biology. Management focuses on tumor and hormonal burden reduction. Data on cytoreduction with extrahepatic disease remain limited.

Objective: We sought to define the outcomes of cytoreduction for metastatic NETs with extrahepatic metastases.

Methods: Patients undergoing cytoreductive surgery for grade 1 or 2 NETs with extrahepatic metastases (with or without intrahepatic disease) were identified from an institutional database (2003-2014). Primary outcomes included postoperative hormonal response (> 50% urinary 5HIAA decrease), progression-free survival (PFS) and overall survival (OS), while secondary outcomes were 30-day postoperative major morbidity (Clavien grade III-V), mortality, and length of stay.

Results: Fifty-five patients were identified (median age 59.3 years, 80% small bowel primaries, 56.4% grade 1); 87% of patients presented with combined intra- and extrahepatic metastases. Resection most commonly included the liver (87%), small bowel (22%), mesenteric (25%) and retroperitoneal (11%) lymph nodes, and peritoneum (7%). Thirty-day major morbidity (Clavien III-V) was 18%, with 3.6% mortality, and median length of stay was 7 days [interquartile range (IQR) 5-9]. Liver embolization was performed in 31% of patients after surgery, at a median of 23 months following surgery. Overall, postoperative hormonal response occurred in 70% of patients. At median follow-up of 37 months (IQR range 22-93), 42 (76%) patients were alive and 23 (41.8%) had progressed. Five-year OS was 77% and 5-year PFS was 51%.

Conclusion: Patients undergoing cytoreduction of metastatic well-differentiated NET in the setting of extrahepatic metastatic disease experience good tumoral control with favorable PFS and OS. Cytoreductive surgery can be safely included in the therapeutic armamentarium for NET with extrahepatic metastases.