Impact of Immune Checkpoint Inhibitor Therapy on The Overall Survival in Elderly Patients With Non-Small Cell Lung Cancer

Abstract Purpose: We analyzed the relationship between a history of immune checkpoint inhibitor and overall survival in patients with non-small cell lung cancer (NSCLC) aged ≥ 70 years. Methods: We conducted a retrospective analysis of the data of patients with NSCLC aged ≥70 years old who had received systemic anticancer therapy at our institution between 2015 and 2019. Results: The analysis included the data of a total of 63 patients, including 36 patients who had received immune checkpoint inhibitor therapy and 27 patients who had not received treatment with an immune checkpoint inhibitor. Univariate analysis revealed a longer overall survival in patients who had received treatment with an immune checkpoint inhibitor as compared to those who had not received treatment with an immune checkpoint inhibitor (median: 17.2 vs. 9.8 months; p = 0.026, log-rank test). Multivariate analysis revealed a significant association between a history of treatment with immune checkpoint inhibitors and the overall survival (hazard ratio, 95% confidence interval: 0.42, 0.20-0.86; p = 0.019, Cox proportional hazards model). A significant interaction was also observed between a history of treatment with an immune checkpoint inhibitor and the tumor histology (p = 0.006), the association between the overall survival and a history of immune checkpoint inhibitor therapy being stronger in the non-small cell lung cancer patients with squamous cell carcinoma than in those with adenocarcinoma. Conclusion: A significant association between history of immune checkpoint inhibitor therapy and the overall survival was detected in elderly NSCLC patients aged ≥70 years old in a clinical practice setting. Our results also suggested that the impact of immune checkpoint inhibitor therapy on the survival differed depending on the tumor histology.