Older patients more likely to die from cancer-related diseases than younger with stage IA non-small cell lung cancer: a SEER database analysis

Background: Various reports showed some conflicting data on survival at different ages. This study aimed to investigate the main cause of death in older patients with lung cancer and to perform a comparison with younger patients in order to observe the differences between these two cohorts. Methods: Outcomes of patients with stage IA non-small cell lung cancer (NSCLC) <_3 cm who underwent lobectomy without induction therapy in the Surveillance, Epidemiology, and End Results-18 (SEER-18; January 2004 to December 2016) database were evaluated using multivariable Cox proportional hazards modeling and propensity score-matched analysis. Results: A total of 16,672 eligible NSCLC cases were found in the SEER database. The number of patients aged <_60, 61-70, and >_71 years was 3,930, 6,391, and 6,351, respectively. Among these patient groups, 527 (13.4%), 1,018 (15.9%), and 1,235 (19.4%) died of lung cancer during follow-up, while 357 (9.1%), 964 (15.1%) and 1,579 (25.2%) died of non-lung cancer diseases, respectively. The overall survival (OS) and lung cancer-specific survival (LCSS) rates of younger patients showed a significant survival advantage over older patients. After propensity-score matching (PSM) of patients aged <_60 and >_71 years using a ratio of 1:1, we found that 403 (12.9%) and 584 (18.7%) patients in the <_60 and >_71 years age groups died of lung cancer, respectively. The OS and LCSS rates of younger patients still exhibited a significant survival advantage over older patients. Conclusions: Older patients with stage IA NSCLC have a worse prognosis compared with younger patients. Also, cancer-related causes were more frequent in older patients than non-cancer-related causes.