P2.16-34 Visceral Pleural Invasion is Closely Associated with Nodal Spread in cStage IA Lung Adenocarcinoma

Abstract

Survival outcomes of patients with clinical Stage IA (cIA) lung adenocarcinoma (LAD) are favorable after resections. In this decade, limited resection without lymphnodes dissections have been indicated for selected cases based on the radiological findings and intraoperative hilar explorations, while we sometimes experience occult lymphnodes metastases among them. These facts refer that limited resections could potentially induce underestimation of the disease, local failure and worsened patients’ prognoses. In the present study, we retrospectively investigate the clinicopathological and oncogenic factors in association with the occult nodal spread and skip metastases, and aim to identify population for standard resection in cIA LAD. We retrospectively investigated 287 patients with cIA LAD who underwent standard pulmonary resections with mediastinal dissections from January 2013 through December 2017. Clinicopathological factors including location of the tumor, radiological pleural invasion and oncogenic status (EGFR/KRAS/ALK/Triple Negative) were reviewed for outcomes of occult nodal spread and skip metastasis. According to the ROC curves analyses, cutoff values of total diameter (TD), solid diameter (SD), mediastinal window diameter (MD) in CT image and pathological invasive size (IS) were settled to diagnose nodal metastases and skip pN2, respectively. Among 287 patients with cIA LAD, 34 (11.8%) with lymph node metastases and 8 (2.8%) with pN2 without hilar metastases (skip pN2) were identified. Univariate analyses revealed that high serum CEA level, TD, MD, SUVmax, IS and pathological pleural invasion (pl) were predictive for nodal metastases. And multivariate analysis showed that pl was closely associated with nodal metastases (Odds Ratio: 3.3, p=0.007). Furthermore, multivariate analysis following the univariate analyses also showed that presence of pl was the factor closely associated with skip N2 metastases (Odds Ratio: 5.7, p=0.029), whereas radiological findings nor oncogenic status were not so. In the clinical valuables, serum CEA level, SD, MD, SUVmax were significantly associated with pl. In resected cIA LAD, pathological pleural invasion was closely associated with both occult nodal spread and skip pN2, while any other preoperative factors and oncogenic status were not. New diagnostic modalities for pl may provide the candidates for standard resections in cIA LAD.