Clinical significance of 4 L lymphadenectomy in solid dominant clinical stage I non-small cell lung cancer in the left upper lobe

Objectives: The significance of station 4 L lymph node dissection (LND) for early-stage non-small cell lung cancer (NSCLC) is unknown. Methods: We evaluated 342 patients who underwent complete anatomical resection and mediastinal LND for radiologically solid dominant clinical (c)-Stage I left upper lobe NSCLC between 2008 and 2022. Solid dominant was defined as a consolidation tumor ratio >0.5, on thin-section computed tomography. After matching, postoperative complications and outcomes between the 4 L LND and non-4 L LND groups were compared. Predictors of 4 L metastasis was also identified using logistic regression analysis. Results: 4LND was performed in 215 patients (63%), and 4 L metastasis was detected in 11 patients. Matching yielded 108 pairs. Recurrent nerve paralysis was more frequent in the 4LND group (P = 0.02) with no significant differences in the overall survival (OS) (5y OS: 85.2% vs. 86.3%, P = 0.66) and recurrence-free survival (RFS) (5y RFS: 78.4% vs. 78.5%, P = 0.51) between the 4 L LND and non-4 L LND groups. Logistic regression analysis determined solid component size >20 mm (P = 0.02) and pleural indentation (P = 0.02) on computed tomography findings as clinical risk factors for 4 L metastasis. The predictive criteria for 4 L metastasis were defined as solid component size <= 20 mm without pleural indentation (specificity: 100%, positive predictive value: 100%). Conclusions: 4 L LND had a higher frequency of recurrent nerve palsy, although no survival improvement was observed in solid dominant c-Stage I left upper NSCLC. 4 L LND may be omitted for solid component size <= 20 mm without pleural indentation.