Lymphadenectomy for clinical early-stage non-small-cell lung cancer: a systematic review and meta-analysis

The benefits of different methods of lymphadenectomy for early-stage non-small-cell lung cancer (NSCLC) remain controversial. Herein, we performed a systematic review and meta-analysis comparing survival benefits of systematic nodal dissection (SND) with those of lymph nodal sampling (LNS) and lobe-specific nodal dissection (L-SND). PubMed, OVID, EBSCO and Springer were searched up to August 2015 for English language studies. Data of selected studies were extracted. Study quality, publication bias and heterogeneity were assessed. Analysis was performed using a random-effects model. A total of 12 studies were identified [4 randomized prospective clinical trials (RCTs) and 8 observational trials] that reported surgical outcomes of 3955 patients with resectable clinical N2 negative NSCLC: 2142 underwent SND and 1813 underwent LNS/L-SND. In the cohort studies, the SND group had a statistically significant improvement in overall survival (OS) [hazard ratios (HRs), 1.24; 95% confidence interval (CI) 1.02-1.5] and recurrence-free survival (RFS) rates (HR, 1.27; 95% CI 1.03-1.58). The pooled HR from RCTs showed a consistent tendency in terms of OS (HR = 1.13, 95% CI 0.94-1.35) and RFS (HR = 0.99, 95% CI 0.82-1.19), in spite of a non-significant difference. In subgroup analyses, the SND group had a statistically significant improvement in OS (HR, 1.40; 95% CI 1.12-1.76) and RFS (HR, 1.5; 95% CI 1.09-2.08) in cohort studies, and a consistent tendency of OS in RCTs (HR = 1.12, 95% CI 0.93-1.35) with non-significant difference. However, there was no significant difference in OS (HR, 1.02; 95% CI 0.66-1.57) and RFS (HR, 1.11; 95% CI 0.87-1.42) between the SND and L-SND group. In early-stage NSCLC patients, LNS was associated with inferior survival rates, while L-SND seemed to provide equal survival benefits compared with SND, and the indications need to be identified.