Impact of examined lymph node count for oesophageal squamous cell carcinoma in patients who underwent left transthoracic oesophagectomy.

Background: The impact of the number of examined lymph nodes (ELNs) on stage correction and prognostication in patients with oesophageal squamous cell carcinoma (ESCC) who underwent left transthoracic oesophagectomy is still unclear.

Methods: Patients with ESCC who underwent left transthoracic oesophagectomy at Sun Yat-sen University Cancer Center between January 1997 and December 2013 were retrospectively enrolled. The Cox proportional hazards regression model was used to determine the effect of ELN count on overall survival (OS). The association between ELN count and nodal status was investigated through scatter plot and binary logistic regression analyses. The impact of ELN count on stage correction was evaluated using the hypergeometric distribution and Bayes theorem. The threshold of ELNs was determined using the LOWESS smoother and piecewise linear regression.

Results: Among the 1826 included patients, greater ELNs were associated with a higher rate of nodal metastasis (adjusted OR = 1.018). When the ELN count increased, the omission rate of positive lymph nodes (LNs) decreased. The ELN count did not impact 90-day mortality but significantly impacted long-term survival (adjusted HR = 0.983), especially in those with node-negative disease (adjust HR = 0.972). In patients with node-negative disease, cut point analysis showed a threshold ELN count of 18.

Conclusions: A greater number of ELNs is associated with more accurate node staging and better long-term survival in resected ESCC patients. We recommended harvesting at least 18 LNs to acquire accurate staging and long-term survival information for patients with declared node-negative disease in the left thoracic approach.