# Neuroendocrine Neoplasms of the Esophagus and Esophagogastric Junction in Germany, 2009–2023

## TL;DR

This study analyzed data from over 2000 German patients to show that the grading of esophageal neuroendocrine tumors strongly affects survival rates.

## Contribution

The study provides the first large-scale population-based evidence on the prognostic impact of grading in esophageal neuroendocrine tumors.

## Key findings

- NET-G1 tumors had a 5-year relative survival of 83.8%, while NET-G3 tumors had only 9.0%.
- Neuroendocrine carcinomas had a 5-year survival of 12.5%, worse than adenocarcinomas and squamous cell carcinomas.
- The incidence of esophageal neuroendocrine neoplasms increased over time in Germany.

## Abstract

Until recently, the influence of the grading of neuroendocrine tumors (G1–G3) of the esophagus on prognosis could not be assessed due to limited data. We used all cancer registry data from Germany (population of 83 million people) in order to assemble the largest possible cohort of patients with these tumors and included 2025 newly diagnosed patients with esophageal or esophagogastric neuroendocrine neoplasms (394 neuroendocrine tumors (NET), 1415 neuroendocrine carcinomas, and 216 mixed neuroendocrine neoplasias in Germany 2009–2023. In the survival analyses of 1320 neuroendocrine neoplasms, we found that the grading of NETs has a strong influence on prognosis. Patients with NET-G1 tumors had a relative 5-year survival of 83.8%, while patients with NET-G2 and NET-G3 tumors had relative survival of 50.0% and 9.0%, respectively. Relative 5-year survival was 12.5% and 25.3% for neuroendocrine carcinomas and mixed neuroendocrine neoplasms, respectively.

Background: The influence of the grading of esophageal neuroendocrine neoplasms (NENs) on prognosis has so far only been investigated in small groups. The aim was to determine the incidence and relative survival of NENs and its subtypes of the esophagus. Methods: We included incident cancers of the esophagus and esophagogastric junction (EGJ) for the years 2009–2023, registered by German cancer registries. NENs were subdivided into neuroendocrine tumors (NETs), neuroendocrine carcinomas (NECs), and mixed forms (MiNENs). To compare the epidemiology of NENs with that of adenocarcinoma and squamous cell carcinoma, we also evaluated these entities in a statistically identical manner. We estimated age-standardized incidence rates (cases per million person-years, old European standard) and 5-year relative survival (period analysis). Results: Of the 2025 NENs of the esophagus and EGJ, 69.9% were NECs, 19.5% were NETs, and 10.7% were MiNENs. 45.0% of NENs occurred at the EGJ. The mean age at diagnosis of esophageal NEN was 67 years. The age-standardized incidence of NEN and the subgroups increased over time, with NEN incidences of 1.1 and 0.4 in 2019 and 2023. Relative survival based on 1320 NENs was 22.8%, with NETs having a markedly better prognosis (59.8%) than NECs (12.5%) and MiNENs falling in between (25.3%). Patients with NET-G1 tumors had a relative survival of 83.8%, while patients with NET-G2 and NET-G3 tumors had relative survival of 50.0% and 9.0%, respectively. Conclusions: Even though accurate diagnosis and coding of NENs is difficult, grading of esophageal NETs has a strong influence on prognosis. Esophageal and esophagogastric NECs have a poorer 5-year relative survival than adenocarcinomas and squamous cell carcinomas.