P2.17-42 Surgical Choice for Clinical Stage IA Non-Small Cell Lung Cancer: Novel Rationale from Intrapulmonary Lymph Node Metastasis Pattern

Abstract

Current available surgical resection methods for early-stage NSCLC mainly consisted of lobectomy and sublobar resection (including segmentectomy and wedge resection) with lobectomy being the preferred option, which was established by the only completed RCT study finding that sublobar resection yielded a significantly higher recurrence rate and a trend toward worse survival than lobectomy. However, there are growing interest in observational studies and systematic reviews exploring the efficacy of sublobar resection in treating early-stage NSCLC, aiming to justify for applying sublobar resection as an alternative to lobectomy for treating these patients but with conflicting conclusions. We aimed to investigate the pattern of intrapulmonary lymph node (LN) metastasis of clinical T1N0M0 peripheral non-small cell lung cancer (NSCLC) to provide novel rationale for surgical choice (lobectomy, segmentectomy, or wedge resection) for these patients. We retrospectively collected clinical data of patients undergoing lobectomy with systematic mediastinal LN dissection or sampling for early-stage NSCLC from January 2015 to December 2018. The intrapulmonary LN metastasis pattern was analyzed by tumor size. We included a total of 354 patients for final analysis. The rate of intrapulmonary LN metastasis was 13.6% (Table 1). When stratified by tumor size, NSCLC ≤1cm had no hilar/intrapulmonary LN metastasis while NSCLC >2 but ≤3cm had significantly high rates of hilar/intrapulmonary LN metastasis (18.4%) and the rates of hilar, interlobar and peripheral LN metastasis were relatively high (5.4%, 5.4% and 12.2%, respectively). NSCLC >1.5cm but ≤2cm also had a relatively high rate of hilar (6.5%) and peripheral (18.3%) LN metastasis while NSCLC >1cm but ≤1.5cm had a significantly low rate of hillar/intrapulmonary (2.5%) and peripheral (2.5%) LN metastasis.Table 1Intrapulmonary lymph node metastasis pattern among clinical stage IA (cT1N0M0) peripheral non-small cell lung cancers with different tumor size.CharacteristicsTotal (N=354)Tumor size groupP value≤1cm (N=35)>1cm but ≤2cm (N=172)>2cm but ≤3cm (N=147)Total dissected N1 LN number (Mean±SD)5.6±3.03.6±1.95.4±2.76.3±3.3<0.001Total dissected N2 LN number (Mean±SD)8.1±4.07.0±3.47.6±3.68.8±4.40.008Lymph node metastasis rate16.9% (60/354)0 (0/35)14.5% (25/172)23.8% (35/147)0.002N1 LN metastasis rate (10-14#)13.6%(48/354)0(0/35)12.2%(21/172)18.4%(27/147)0.013Hilar LN metastasis rate (10#)4.2%(15/354)0(0/35)4.1%(7/172)5.4%(8/147)0.348Interlobar LN metastasis rate (11#)3.4%(12/354)0(0/35)2.3%(4/172)5.4%(8/147)0.263*Peripheral LN metastasis rate (12-14#)10.5%(37/354)0(0/35)11.0%(19/172)12.2%(18/147)0.092N2 LN metastasis rate (1-9#)8.8%(31/354)0(0/35)8.1%(14/172)11.6%(17/147)0.088Note: LN=lymph node; SD=standard deviation. *Fisher’s exact test Open table in a new tab Note: LN=lymph node; SD=standard deviation. *Fisher’s exact test Based on the pattern of intrapulmonary LN metastasis, our study provided novel perspectives on surgical choice of lobectomy, segmentectomy, or wedge resection for clinical stage IA peripheral NSCLC: for NSCLC ≤1cm both segmentecotmy and wedge resection could be utilized, and for NSCLC >1cm but ≤1.5cm segmentecotmy could be utilized provided that sufficient resection margin could be achieved; while for NSCLC >1.5cm lobectomy should be the preferred surgical option.