Impact of number of dissected lymph nodes on long-term survival in lung adenocarcinoma with mixed ground-glass opacity

Background Dissection of intra-pulmonary and mediastinal lymph nodes (N1 and N2) is recommended by NCCN guidelines for patients with non-small cell lung cancer (NSCLC). However, recent studies suggest that extensive lymph node dissection (LND) may not be necessary for all cases. The optimal scope and clinical benefit of LND in routine surgical practice remain under debate. Methods A total of 484 consecutive patients with clinical stage IA lung adenocarcinoma presenting as mixed ground-glass opacity (mGGO) underwent surgical resection between July 2008 and November 2020. Three patients were excluded due to postoperative confirmation of pleural invasion. Follow-up was performed monthly until loss to follow-up or December 31, 2023. Kaplan–Meier curves and the log-rank test were used for univariate analysis, and a Cox proportional hazards model with forward stepwise selection was used for multivariate analysis. Optimal cut-off numbers of dissected lymph nodes associated with recurrence-free survival (RFS) and overall survival (OS) were identified. Results The median follow-up times for RFS and OS were 47.2 and 47.9 months, respectively. The best cut-off numbers of dissected lymph nodes associated with survival were 8 for T1, 20 for T1a, and 5 for T1b disease. For the overall T1 cohort, no significant differences in RFS (p = 0.23) or OS (p = 0.26) were observed between patients with fewer than 8 versus more than 8 lymph nodes dissected. In T1a, patients with more than 20 nodes dissected did not show significantly better RFS (p = 0.25) or OS (p = 0.095); however, in the subgroup with a consolidation tumor ratio (CTR) > 0.25, greater node dissection was associated with improved RFS (p = 0.041). In T1b, dissection of more than 5 nodes was significantly associated with better RFS and OS (both p = 0.0041). The cut-off value of 8 lymph nodes, determined via log-rank test, aligned with findings from previous literature. Multivariate analysis showed that the number of dissected lymph nodes (<8 vs. ≥8) was not an independent prognostic factor for RFS (p = 0.214). Conclusions This study aimed to explore the optimal lymph node dissection strategy in stage IA NSCLC with mixed GGO. For overall T1-stage patients, the number of dissected lymph nodes did not significantly affect long-term RFS or OS. In T1a patients, particularly those with GGO-predominant lesions, extensive LND may be unnecessary. Conversely, in T1b patients, dissection of at least five lymph nodes is recommended to achieve better oncologic outcomes and ensure surgical completeness.