Prognostic factors for survival in patients with metastatic lung adenocarcinoma: An analysis of the SEER database

BACKGROUND: Lung adenocarcinoma (ADC) is the main cause of death related to lung cancer. The aim of this study was to identify poor prognostic factors for overall survival (OS) in patients with stage IV lung ADC in real‐world clinical practice. METHODS: Patients were selected from the Surveillance Epidemiology and End Results (SEER) database. Chi‐square bivariate analysis was used for the association of binary qualitative variables. A multivariate Cox regression analysis was performed to determine the impact of these prognostic factors on OS. RESULTS: A total of 46 030 patients were included (51.3% men, mean age 67.03 ± 11.6), of whom 41.3% presented with metastases in bone, 28.9% in brain, 17.1% in liver and 31.8% in lung. Patients with liver metastases presented with two or more metastatic sites more frequently than patients without liver metastases (P < 0.001). Male sex (HR 0.78, 95% CI: 0.76–0.80), age ≥ 65 years (HR 1.37, 95% CI: 1.33–1.40), lack of family support (HR 0.80, 95% CI: 0.78–0.81) and presence of liver (HR 1.45, 95% CI: 1.40–1.50), bone (HR 1.21, 95% CI: 1.18–1.24) or brain metastases (HR 1.18, 95% CI: 1.15–1.21) were identified as poor prognostic factors for OS. Patients with liver metastasis showed the highest hazard ratio value (P < 0.001). CONCLUSIONS: The presence of liver metastases was the worst prognostic factor for patients with metastatic lung ADC. This factor should be considered as a stratification factor for future studies evaluating new cancer treatments including immunotherapy. KEY POINTS: SIGNIFICANT FINDINGS OF THE STUDY: Regression analysis identified poor prognostic factors for overall survival. Factors were male sex, age ≥ 65 years, lack of family support and presence of liver, bone and brain metastases. Patients with liver metastasis showed the highest HR (HR = 1.45 95% CI: 1.40–1.50). This study included the highest number of adenocarcinoma patients analyzed so far (N = 46 030). What this study adds: The presence of liver metastases should be considered as a stratification factor for future studies evaluating new cancer treatments including immunotherapy.