Abstract 2363: Impact of the IASLC/ATS/ERS lung adenocarcinoma classification on death and recurrence in resected lung adenocarcinoma.
Authors: Hung Jung-Jyh , Chou Teh-Ying , Hsu Wen-Hu , Wu Yu-Chung 
Published: August 2014

Abstract
Objective: Lung cancer is the leading cause of cancer death worldwide. Adenocarcinoma is the most common histological type of non-small cell lung cancer. The International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS), and the European Respiratory Society (ERS) proposed a new classification system of lung adenocarcinoma in 2011. This study investigated the prognostic value of the new IASLC/ATS/ERS adenocarcinoma classification in resected lung adenocarcinoma.
Methods: Histological classification of 422 patients undergoing surgical resection for stage I-IV adenocarcinoma was determined according to the IASLC/ATS/ERS classification with recording of the percentage of each histologic component (lepidic, acinar, papillary, micropapillary, and solid) in 5% increments. The predominant pattern is defined according to the most dominant pattern. The relationship between the predominant pattern and conventional clinicopathological variables was demonstrated. Their impact on overall survival (OS) and disease-free survival (DFS) was also investigated.
Results: The median follow-up time for all the 422 patients was 53.0 months (mean, 53.6 ± 25.4 months). There are 45 (10.7%) patients with lepidic predominant, 128 (30.4%) with acinar predominant, 130 (30.8%) with papillary predominant, 62 (14.7%) with micropapillary predominant, and 57 (13.5%) with solid predominant adenocarcinomas. The solid predominant group is associated with significant greater tumor size (P&lt; 0.001), less T1a disease (P= 0.003), more N2 disease (P&lt; 0.001), less stage IA and more stage IIIA disease (P&lt; 0.001), more visceral pleural invasion (P= 0.005), more angiolymphatic invasion (P= 0.001), and more poorly differentiated histologic grade (P&lt; 0.001). OS and DFS in solid predominant group are significantly shorter than other four predominant groups (P&lt; 0.001, P&lt; 0.001, respectively). Older age (P= 0.020), greater tumor size (P= 0.003), advanced TNM stage (P&lt; 0.001), angiolymphatic invasion (P= 0.008), adjuvant chemotherapy (P&lt; 0.001), and IASLC/ATS/ERS predominant pattern (P= 0.004) are significant predictors of worse OS in multivariate analysis. Older age (P= 0.013), greater tumor size (P= 0.040), advanced TNM stage (P&lt; 0.001), angiolymphatic invasion (P&lt; 0.001), adjuvant chemotherapy (P= 0.003), and IASLC/ATS/ERS predominant pattern (P= 0.024) are also significant predictors of worse DFS in multivariate analysis.
Conclusions: The IASLC/ATS/ERS predominant pattern is a stage independent predictor for OS and DFS in resected lung adenocarcinoma. Patients with solid predominant type have significant higher risk for death and recurrence after operation. This information is important for patient stratification for aggressive adjuvant chemoradiation therapy.
Citation Format: Jung-Jyh Hung, Teh-Ying Chou, Wen-Hu Hsu, Yu-Chung Wu. Impact of the IASLC/ATS/ERS lung adenocarcinoma classification on death and recurrence in resected lung adenocarcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2363. doi:10.1158/1538-7445.AM2013-2363