The prognostic value of 4L lymph node dissection in left-side operable non-small-cell lung cancer: a meta-analysis

The prognostic value of 4L lymph node dissection (4L-LND) continues to be controversial. We conducted this systematic review and meta-analysis to evaluate the prognosis of 4L-LND in operable non-small-cell lung cancer (NSCLC) patients. We systematically searched studies from PubMed, Embase, and the Cochrane Library up to May 1, 2023. Studies investigating the prognostic value of 4L-LND and non-4L-LND in NSCLC survival were included. Data for analysis mainly comprised postoperative complications, overall survival (OS), and disease-free survival (DFS). The Q-test and I²-test were used to assess heterogeneity. The stability of pooled hazard ratios (HRs) was examined by sensitivity analysis. Six retrospective studies with a total of 4565 NSCLC patients who received 4L-LND or did not receive 4L-LND were considered. The 4L-LND group had significantly better OS (HR = 0.75, 95% CI 0.61-0.91, P = 0.004) and DFS (HR = 0.76, 95% CI 0.66-0.88, P = 0.0002) than the non-4L-LND group, especially in the subgroup analysis of propensity score matching studies. Although no significant difference in the rate of chest tube drainage for more than 7 days (risk ratio (RR) = 0.98, 95% CI 0.31-3.08, P = 0.97), hoarseness rate (RR = 1.60, 95% CI 0.53-4.87, P = 0.51), and chylothorax rate (RR = 1.28, 95% CI 0.58-2.84, P = 0.54) was observed, those who received 4L-LND had a higher total postoperative complication rate than those who did not (RR = 1.35, 95% CI 1.09-1.67, P = 0.006). No significant heterogeneity existed during our analysis, and no potential publication bias was observed among these studies. Our meta-analysis showed that the 4L-LND group was significantly associated with both survival outcomes and postoperative complications compared with the non-4L-LND group in treating NSCLC patients. However, further prospective clinical trials should be designed to evaluate our conclusion owing to the lack of guideline support.