Serum neuron-specific enolase level is an independent predictor of overall survival in patients with gastroenteropancreatic neuroendocrine tumors

Serum neuron-specific enolase (NSE) is considered a tumor marker in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs). It is elevated in 30%–50% of GEPNET patients and correlates with tumor size. NSE has a sensitivity of 38% and specificity of 73% for GEP-NET detection. The prognostic role of serum NSE as a biomarker for GEPNETs patients’ survival is poorly studied. We retrospectively studied 592 patients with sporadic (nonfamilial) ENETS TNM stage IV GEP-NETs. Median follow-up was 58.7 months (25th–75th percentile: 34.02–92.98). Serum NSE was measured at first consultation, using enzyme immunoassay (NSE Cobas E602, Roche Diagnostics,Mannheim, Germany). Cutoff values for serum NSE were: NSE ≤1× ULN (≤16.2 μg/ l), NSE 1–3× ULN (16.2–48.6 μg/l) and NSE >3× ULN (48.6 μg/l). Primary outcome was overall survival, calculated from date of diagnosis to date of death by any cause, or date of last follow-up. Using statistical software R version 3.1.3 ‘survival’ package, overall survival was estimated with the Kaplan–Meier method. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated with Cox proportional hazards models including age at diagnosis, OctreoScan® (SRS) positivity (Krenning Scale ≥2 in all lesions), primary tumor site, sex and bone metastases. Two hundred forty-two (41%) of GEP-NET patients had an elevated NSE (>1× ULN). NSE >3× ULN were seen in pancreatic NETs. [...]