Clinical characteristics, prognostic factors, and survival trends in esophageal neuroendocrine carcinomas: A population‐based study

BACKGROUND: Esophageal neuroendocrine carcinoma (ENEC) is an extremely rare type of malignancy. Clinical data of ENEC are limited to case reports and case series. More information is needed on its clinical feature, management, and prognosis. METHODS: This study collected information of ENEC patients diagnosed pathologically from 2010 to 2018. Data including demographic information, clinical features, and survival trends were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Statistical analyses were performed with STATA/SE 15.1, SPSS 25.0, and GraphPad Prism 8. RESULTS: A total of 283 ENEC patients were included in this study. The small‐cell and large‐cell subtypes of ENEC possess similar clinical features. The lower third of the esophagus (58%) was the most common location of ENEC. At the time of diagnosis, most ENEC patients were AJCC 7th stage IV (48.1%). Metastasis occurred in more than half of the ENEC patients (53.4%), and the most common metastatic site was the liver (37.1%). Compared with poorly differentiated esophageal squamous cell carcinoma (ESCC), another aggressive malignancy of the esophagus sometimes confused with ENEC because of similar histological features, our study showed differences in tumor location and metastatic rate, but similar poor survival rates. Multivariate survival analysis showed that ENEC located at the middle third of esophagus (p = 0.013), “Brain metastasis” (p = 0.019), and “Liver metastasis” (p < 0.001) were independent predictors of worse outcomes. “Surgery” (p = 0.003), and “Chemotherapy” (p < 0.001) were associated with better survival. CONCLUSION: A significant proportion of patients with newly diagnosed ENEC presented with metastatic disease. Predictors of poor survival included tumor location, brain metastasis, and liver metastasis. ENEC and poorly differentiated ESCC share certain histological features, but differ in tumor location and metastatic rate. Yet, no standard treatment strategy has been established, but surgery and chemotherapy were related to better outcomes.