Lymph node dissection of station 8 improves the survival of T ≤3 cm N0M0 lung adenocarcinoma patients

Background: Mediastinal station 8 lymph node dissection (8LND) is recommended by guidelines but not routinely performed in real world clinical practice. This study aimed to investigate the effect of 8LND on the prognosis of pT <= 3 cmN0M0 lung adenocarcinoma. Methods: Patients undergoing lobectomy were retrospectively enrolled from West China Hospital from 2011 to 2019. Kaplan-Meier method and log-rank test were used to investigate the effects of 8LND on the progression-free survival (PFS), overall survival (OS), and cancer-specific survival (CSS). Propensity score matching (PSM) was used to reduce the confounding effects. Multivariable analysis was conducted to evaluate the effect of 8LND in the matched patients. Subgroup analyses were conducted to further identify patients who might benefit from 8LND. Results: A total of 1,209 patients were enrolled and 261 (21.59%) patients underwent 8LND. Before PSM, for patients who received 8LND (8LND+ patients) and who did not (8LND- patients), the 5-year PFS was 91.34%, 88.03% (P=0.03) respectively, the 5-year OS was 97.10%, 92.78% (P=0.03) respectively, and the 5-year CSS was 97.67%, 93.59% (P=0.05) respectively. After PSM, 8LND+ patients still had better PFS (P=0.006), OS (P=0.01), and CSS (P=0.03) as compared to 8LND- patients. Multivariable analyses showed that 8LND was associated with lower risk of disease progression [hazard ratio (HR): 0.46; 95% confidence interval (CI): 0.26-0.80; P=0.007], and lower risk of death (HR: 0.33; 95% CI: 0.13-0.85; P=0.02). The survival benefit of 8LND was still found in subgroup analyses in male patients, smokers, patients with a pT2 tumor (<= 3 cm), and patients with a poorly differentiated tumor. Conclusions: 8LND could improve the survival of T <= 3 cmN0M0 lung adenocarcinoma patients. Routine 8LND is recommended, especially in male, smokers, patients with a pT2 tumor (<= 3 cm), and patients with a poorly differentiated tumor.