60P Comparison of metastasis patterns and prognosis of advanced old NSCLC patients by age groups: A SEER database analysis

We aimed to investigate the different metastatic patterns and corresponding survival outcomes between early age of elderly (aged between 65 to 80 years) and late age of elderly (aged more than 80 years) stage IV NSCLC patients. Stage IV old NSCLC patients from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2016 were divided into an early age and late age of elderly group. To reduce the bias of retrospective studies, propensity score matching (PSM) analysis was performed. Baseline characteristics of patients were analyzed by the t test and chi- square test. Overall survival (OS) and lung cancer specific survival (LCSS) were evaluated by Kaplan-Meier curves and Cox proportional hazards models. Univariate and multivariate Cox regression models were used to analyze survival outcomes and other prognostic factors. Finally, a nomogram was constructed and validated to predict patient survival time. From the SEER database, a total of 47 438 old patients with stage IV NSCLC from 2010 to 2016 were enrolled in this cohort study. X-tile analysis identified the optimal cutoff age for LCSS as 80 years old. In this study, 35 385 patients aged 65–80 years and 12 052 patients aged over 85 years were included. After 1:1 PSM analysis, 10 931 patients aged 65–80 years and 10 931 patients aged over 85 years were ultimately included. Adenocarcinoma was the dominant histological subtype across each age group, particularly in the younger group. With aging, the proportion of patients undergoing treatment, including surgery, radiation, and chemotherapy, progressively declined. Compared with younger NSCLC patients, lung metastases were significantly more frequent in the elderly group, and lung metastases and distant lymph nodes metastases were independent prognostic factors of LCSS [lung metastases: hazard ratio (HR): 0.890; distant lymph nodes metastases: hazard ratio (HR): 0.844, all P values were <0.001]. In each age subgroup, patients with multi-organ metastasis had the worst LCSS. Various clinicopathological features and prognostic values are associated with different metastatic sites. Understanding these differences may enable targeted pre-treatment assessment of advanced old NSCLC.