Disparities in survival following surgery among patients with different histological types of N2-III non-small cell lung cancer: a Surveillance, Epidemiology and End Results (SEER) database analysis

BACKGROUND: This study aimed to determine the extent to which the survival outcomes of patients with N2-III non-small cell lung cancer (NSCLC) following surgery differ by histological subtype. METHODS: Patients with N2-III NSCLC receiving surgery between 2010 to 2016 were included using the Surveillance, Epidemiology and End Results (SEER) database. Cox proportional hazards models were used to identify risk factors associated with overall survival (OS) and non-cancer mortality. The Kaplan-Meier method with log-rank tests was used to estimate survival. Propensity score matching (PSM) was used. Statistical significance was defined as P<0.05. Statistical analyses were done with IBM SPSS 23.0. RESULTS: Ultimately, 2,501 patients with stage N2-III NSCLC receiving surgery were included: 1,891 (75.6%) patients had adenocarcinoma (AC), and 610 (24.4%) patients had squamous cell cancer (SCC). The percentages of patients with AC and SCC receiving chemotherapy and postoperative radiotherapy (PORT) were comparable. In multivariate analysis, histology remained a significant predictor for OS and non-cancer mortality after adjusting for other clinical factors (P<0.05). Based on clinical factors, 522 patients with SCC were ultimately matched with 518 patients with AC using PSM. The 5-year OS of SCC patients after matching was much worse than that of AC patients (36.3% vs. 41.5%; P=0.018), and the 5-year non-cancer mortality of SCC patients was much higher than that of AC patients (18.8% vs. 4.8%; P=0.001). CONCLUSIONS: Among patients with stage N2-III NSCLC following surgery, those with SCC had worse OS than those with AC, due to the higher percentage of patients dying from non-cancer causes.