Dissection of 4L lymph node for left-sided non-small cell lung cancer: a meta-analysis

Whether dissection of left lower paratracheal (4L) lymph node has any impact on survival of patients with left-sided non-small cell lung cancer (NSCLC) remains unclear. We conducted the first meta-analysis to compare the survival of patients treated with 4L lymph node dissection (LND) and those without for left-sided NSCLC.

We systematically searched relevant studies from PubMed, Embase, and Web of Science on February 6, 2020. Data for analysis included 5-year overall survival (OS) and disease-free survival (DFS) rates, OS, and DFS. We calculated risk ratio (RR) for pooling 5-year OS and DFS rates and extracted hazard ratio (HR) from multivariate analysis for pooling OS and DFS.

We finally included three retrospective cohort studies with propensity score-matched analysis consisting of 2103 patients. Meta-analysis showed that patients treated with 4L LND yielded significantly higher 5-year OS (67.7% vs. 54.6%; fixed effects models: RR = 0.75; 95% confidence interval [CI] = [0.67, 0.84]; p < 0.001; I²  = 0%) and DFS (53.3% vs. 44.8%; fixed effects models: RR = 0.85; 95% CI = [0.76, 0.95]; p = 0.003; I²  = 41.7%) rates than patients without 4L LNDS. Moreover, dissection of 4L lymph node was significantly associated with better OS (fixed effects model: HR = 0.66; 95% CI = [0.57, 0.76]; p < 0.001; I²  = 45.7%) and DFS (fixed effects model: HR = 0.67; 95% CI = [0.52, 0.87]; p = 0.003; I²  = 0%). No significant heterogeneities were observed.

Dissection of 4L lymph node could significantly improve both 5-year OS and DFS rates and 4L LND was a favorable prognostic factor for patients with left-sided NSCLC.