Association between the novel classification of lung adenocarcinoma subtypes and EGFR/KRAS mutation status: A systematic literature review and pooled-data analysis

This study aims to determine the association of EGFR/KRAS mutation status with histological subtypes of lung adenocarcinoma (LAC) based on the IASLC/ATS/ERS classification.Pubmed and Cochrane databases were searched from January 2011 to June 2018 for studies that included patients with LAC who underwent surgical resection were classified according to the new IASLC/ATS/ERS classification. EGFR/KRAS status assessment was requireded. The primary outcome was determined by the odds ratio (OR) of the incidence of mutation status of certain of each histological subtype. The reference group consisted of EGFR/KRAS mutation negative patients.Twenty-seven eligible studies involving 9022 patients with mutation gene detection were included for analysis. Among them, 6717 (74.5%) patients were from the Asian region and, 2305 (25.5%) patients were from Non-Asian regions. The most prevalent subtype was acinar (34.7%), followed by papillary (22.9%), lepidic (18.9%), solid (13.6%), micropapillary (6.3%), and invasive mucinous adenocarcinoma (3.5%). EGFR mutations were more common in patients with resected lepidic predominant adenocarcinoma (OR,1.76; 95%CI, 1.38-2.24;p < 0.01) and were rarely found in solid predominant adenocarcinoma (OR,0.28; 95%CI, 0.23-0.34;p < 0.01) or IMA (OR,0.10; 95%CI, 0.06-0.14;p < 0.01). Conversely, KRAS mutations were characterized by IMA (OR,7.01; 95%CI, 5.11-9.62;p < 0.01), and were less frequently identified in lepidic (OR,0.58; 95%CI, 0.45-0.75;p < 0.01) and acinar (OR,0.65; 95%CI, 0.55-0.78;p < 0.01) predominant subtypes. Further analyses were performed in Asian and Non-Asian groups and the results were consistent.The current study confirms that the IASLC/ATS/ERS classification is associated with driver gene alterations in resected LAC.