Prognostic significance of the number of lymph nodes dissection in esophageal adenocarcinoma patients

BACKGROUND: Esophagectomy combined with lymphadenectomy has been considered as the preferred treatment option for esophageal cancer (EC). However, for a long time, no consensus is reached on the optimal number and scope of lymph node dissection (LND). In particular, related research on esophageal adenocarcinoma remains lacking at present. To determine the relationship between the number of LND and the prognosis for esophageal adenocarcinoma patients, this study was conducted based on the United States Surveillance, Epidemiology and End Results (SEER) database. METHODS: Data were extracted from esophageal adenocarcinoma patients undergoing esophagectomy from 2000 to 2016 based on the SEER database. Thereafter, the enrolled patients were divided into five groups according to the number of LND, namely, 0, 1–10, 11–20, 21–30 and >30 LNDs groups. Besides, the Kaplan-Meier product method was applied in estimating the impact of LND number on the overall survival (OS) and disease-specific survival (DSS) of patients. Moreover, the Cox proportional hazard model was employed to analyze the covariates that might affect the results. RESULTS: After adjusting for age, gender, race, grade, T stage, tumor location, tumor size and number of positive lymph nodes, differences in OS and DSS were statistically significant among those five groups, and only groups receiving >20 LNDs were related to the improved OS and DSS. Also, it was discovered that, difference in OS was of statistical significance across those five groups in the <50, ≥50 years old, male, Grade I, Grade II, Grade III, T1, T2, T3, and tumor size >4 cm subgroups. CONCLUSIONS: The number of LND can serve as an independent prognostic factor for OS and DSS among esophageal adenocarcinoma patients. In addition, we recommend that esophageal adenocarcinoma patients should undergo LND to dissect at least 20 lymph nodes.