Clinical Significance of 4L Lymph Node Dissection in Left Lung Cancer

To investigate the prognostic impact of 4L lymph node (LN) dissection in left lung cancer and to analyze the relative risk factors for 4L LN metastasis.

We retrospectively collected data from 657 patients with primary left lung cancer who underwent surgical pulmonary resection from January 2005 to December 2009. One hundred thirty-nine patients underwent 4L LN dissection (4L^D+ group); the other 518 patients did not receive 4L LN dissection (4L^D- group). Propensity score weighting was applied to reduce the effects of observed confounding between the two groups. Study end points were disease-free survival (DFS) and overall survival (OS).

The metastasis rate of station 4L was 20.9%, which was significantly higher than those of station 7 (14.0%; P = .048) and station 9 (9.8%; P < .001). Station 4L metastasis was associated with most other LN station metastases in univariate analysis, but only station 10 LN metastasis was an independent risk factor for 4L LN metastasis (odds ratio, 0.253; 95% CI, 0.109 to 0.588; P = .001) in multivariate logistic analysis. The 4L^D+ group had a significantly better survival than the 4L^D- group (5-year DFS, 54.8% v 42.7%; P = .0376; 5-year OS, 58.9% v 47.2%; P = .0200). After allowing potential confounders in multivariate survival analysis, dissection of 4L LN retained its independent favorable effect on DFS (hazard ratio, 1.502; 95% CI, 1.159 to 1.947; P = .002) and OS (hazard ratio, 1.585; 95% CI, 1.222 to 2.057; P = .001). Propensity score weighting further confirmed that the 4L^D+ group had a more favorable DFS ( P = .0014) and OS ( P < .001) than the 4L^D- group.

Station 4L LN involvement is not rare in left lung cancer, and dissection of the 4L LN station seems to be associated with a more favorable prognosis as compared with those who did not undergo this dissection.