P1.17-19 Lobe-Specific Lymph Node Dissection for Clinical Early-Stage (cIA) Peripheral Non-Small Cell Lung Cancer Patients: Feasible and How?

Abstract

Currently, the extent of lobe-specific lymph node (LN) dissection (L-SLND) for early-stage non-small cell lung cancer (NSCLC) in previous literatures remains controversial without well-recognized agreement on exact definition of L-SLND. We aimed to investigate the possible lobe-specific LN metastasis pattern of clinical T1N0M0 peripheral NSCLC and define the extent of L-SLND for them. We retrospectively collected clinical data of patients undergoing lobectomy or segmentectomy with systematic lymphadenectomy for early-stage NSCLC from January 2015 to December 2018. The LN metastasis pattern of them was analyzed by tumor lobe location. A total of 590 patients were included for analysis. The rate of mediastinal LN metastasis was 9.5% (table 1). For cases in the upper lobes and these in the lower lobes, 8.8% and 6.0% of them respectively metastasized to the upper LN zone (P=0.274). However, cases in the upper lobes hardly metastasized to the subcarinal (0.3%) and lower (0.3%) LN zones while it was 10.2% and 5.4% for cases in the lower lobes, respectively (both P<0.001). When stratified by tumor size, all these cases (100%) metastasizing from lower lobes had a tumor size of 2-3 cm while cases with a tumor size ≤2 cm had no metastasis to upper LN zone. For cases in right middle lobe, none of them metastasized to the lower LN zone.Table 1Lymph node metastasis pattern among non-small cell lung cancers in different lobesCharacteristicsTotal (N=590)Right upper lobe (N=220)Right middle lobe (N=48)Right lower lobe (N=84)Left upper lobe (N=156)Left lower lobe (N=82)P valueTotal dissected LN number (Mean±SD)12.3±5.813.0±4.511.3±5.113.3±6.011.1±5.312.1±5.10.008Total dissected mediastinal LN number (Mean±SD)8.2±4.19.1±4.58.7±3.99.2±4.86.8±3.27.1±3.2<0.001LN metastasis rate83 (14.1%)29 (13.2%)8 (16.7%)13 (15.5%)20 (12.8%)13 (15.9%)0.915Upper zone metastasis rate47 (8.0%)16 (7.3%)4 (8.3%)5 (6.0%)17 (10.9%)5 (6.1%)0.586Subcarinal zone metastasis rate22 (3.7%)1 (0.5%)4 (8.3%)11 (13.1%)0 (0%)6 (7.3%)<0.001Lower zone metastasis rate10 (1.7%)1 (0.5%)0 (0%)4 (4.8%)0 (0%)5 (6.1%)0.001Note: LN=lymph node; SD=standard deviation. Open table in a new tab Note: LN=lymph node; SD=standard deviation. A lobe-specific LN metastasis pattern of early-stage peripheral NSCLC was observed and for cases in the upper lobes (≤3cm), there is no need to dissect lower mediastinal LNs and for cases in the lower lobes (≤2cm), there is no need for dissecting upper mediastinal LNs. Otherwise, systematic LN dissection or sampling instead of L-SLND should be recommended.