Validation of stage groupings in the eighth edition of the tumor node metastasis classification for lung adenocarcinoma

Background The purpose of this study was to validate stage groupings in the 8th edition of the tumor node metastasis (TNM) classification for lung adenocarcinoma and explore the non-anatomic factors that influence the prognosis of lung adenocarcinoma patients in China. Methods We retrospectively analyzed the data of 291 lung adenocarcinoma patients at our department between 2008 and 2013. Logrank tests and Cox regression models were used to analyze survival among adjacent stage groupings. Kaplan-Meier curves were used to estimate overall survival (OS). Results There were significant differences in OS in adjacent stage groupings in early stages in the 8th edition. There were also significant differences between patients treated with radical surgery and limited resection (P = 0.027). Lepidic predominant adenocarcinoma (LPA) had better survival rates than acinar predominant (APA), papillary predominant, and solid predominant with mucin production adenocarcinoma (SPA) (P = 0.008). Survival rates of micropapillary predominant adenocarcinoma were lower than the others (P = 0.003). EGFR mutations were closely associated with lepidic predominant (65%, P = 0.56) but less commonly associated with solid predominant with mucin production adenocarcinoma (24%, P = 0.02). There was no significant difference in survival between EGFR gene mutation-positive and negative groups (P = 0.402). Conclusion The 8th edition TNM may be more accurate and applicable than the 7th edition for Chinese lung adenocarcinoma patients who have undergone surgical treatment. Stage IV patients may gain survival improvement from radical surgery.