Abstract
INTRODUCTION: Lung cancer with extrathoracic metastases is classified as M1c. However, extrathoracic metastases can be further classified into different patterns. The purpose of this study was to analyze the survival differences between different patterns of extrathoracic metastases in patients with stage M1c lung adenocarcinoma after receiving immunotherapy. MATERIALS AND METHODS: This study included 160 stage M1c lung adenocarcinoma patients and treated with immunotherapy. The enrolled patients were divided into two groups: those with multiple extrathoracic metastases alone (EM group) and those with simultaneous multiple extrathoracic and intrathoracic metastases (EIM group). Progression-free survival (PFS) and overall survival (OS) were evaluated. RESULTS: The median PFS and OS in the whole group were 7.7 months and 25.4 months, respectively. The patients in the EM group show better PFS (13.0 months vs. 5.0 months; hazard ratio [HR] = 0.462, 95% confidence interval [CI] 0.317-0.673, P < 0.0001) and OS (35.0 months vs. 18.9 months; HR 0.592, 95% CI 0.380-0.922, P = 0.019) compared with the EIM group. Furthermore, in patients with lung adenocarcinoma with simultaneous extrathoracic and intrathoracic metastases who received immunotherapy, immunotherapy combined with chemotherapy has better PFS and OS than immunotherapy alone. There was no difference between immunotherapy alone or combined with chemotherapy in patients with lung adenocarcinoma with extrathoracic metastasis alone. CONCLUSION: The different patterns of extrathoracic metastasis were related to the efficacy and prognosis of immunotherapy in M1c cohort. In addition, patients with simultaneous extrathoracic and intrathoracic metastases were more recommended to choose immunotherapy in combination with chemotherapy rather than immunotherapy alone.