A Real-World, Population-Based Study for the Incidence and Outcomes of Neuroendocrine Neoplasms of Unknown Primary

Neuroendocrinology. 2021;111(9):876-882. doi: 10.1159/000511812. Epub 2020 Sep 25.

Abstract

Objective: The aim of the study was to provide a real-world, population-based assessment of the incidence and outcomes of neuroendocrine neoplasms (NENs) of unknown primary.

Methods: Surveillance, Epidemiology, and End Results registry was accessed, and cases with NENs of unknown primary were reviewed. Rates of NENs diagnosis 1975-2017 according to primary tumor site were also reviewed. Survival outcomes of patients with NENs of unknown primary compared to metastatic NENs with known primary were determined through Kaplan-Meier estimates and multivariable Cox regression analysis. Overall and cancer-specific survival analyses were stratified by primary site and histology (neuroendocrine tumor vs. neuroendocrine carcinoma).

Results: A total of 3,550 cases (7%) were diagnosed with NENs of unknown primary within the study duration. The annual percent change for NENs of unknown primary was 3.4 (95% CI: 2.6-4.2). Within the cohort of metastatic neuroendocrine tumor patients (carcinoid tumor histology), the following factors were associated with a lower risk of death; younger age (HR: 0.477; 95% CI: 0.443-0.513), female sex (HR: 0.922; 95% CI: 0.860-0.989), and small intestinal primary (HR for unknown primary vs. small intestinal primary: 1.532; 95% CI: 1.408-1.668). Within the cohort of metastatic neuroendocrine carcinoma, the following factors were associated with a lower risk of death in this cohort; younger age (HR: 0.646; 95% CI: 0.612-0.681), female sex (HR: 0.843; 95% CI: 0.801-0.888), and small intestinal primary (HR for unknown primary vs. small intestinal primary: 2.961; 95% CI: 2.586-3.391).

Conclusions: The diagnosis of NENs of unknown primary has increased across the past 4 decades. Outcomes of individuals with metastatic small intestinal NENs seem to be better than those with metastatic NENs of unknown primary (for both carcinoid tumors and neuroendocrine carcinomas).

Keywords: Incidence; Neuroendocrine neoplasms; Outcomes; PRUNK.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Female
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Neoplasms, Unknown Primary / epidemiology*
  • Neoplasms, Unknown Primary / therapy*
  • Neuroendocrine Tumors / epidemiology*
  • Neuroendocrine Tumors / therapy*
  • Outcome Assessment, Health Care*