Immune checkpoint inhibitors with or without radiotherapy in metastatic non‑small cell lung cancer: A meta‑analysis and literature review

The combination of immune checkpoint inhibitors (ICIs) and radiotherapy has shown promise in the treatment of metastatic non-small cell lung cancer (NSCLC). The present meta-analysis aimed to determine the efficacy and safety of combining radiotherapy (RT) ICIs for the treatment of metastatic NSCLC. PubMed, Google Scholar, the Cochrane Library and Web of Science databases were searched for relevant articles up to February 1, 2023. Post-therapy outcomes such as progression-free survival (PFS), complete response, partial response (PR), progressive disease (PD), stable disease and adverse events (AEs) were analyzed. The meta-analysis was performed using RevMan 5.4 software. A total of seven studies involving 682 patients were included (384 patients who received ICI + RT vs. RT and 298 patients who received ICI + RT vs. ICI alone). No significant difference in PFS was demonstrated between the ICI + RT group and the RT group (heterogeneity: χ²=2.35; df=1; P=0.13; I²=57% and test for overall effect: Z=0.10; P=0.92). Conversely, patients in the ICI alone group had significantly decreased PR rates (heterogeneity: Τ²=0.00; χ²=2.13; df=3; P=0.54; I²=0% and test for overall effect: Z=2.57; P=0.01) compared with patients in the ICI + RT group. The ICI + RT group also had significantly lower rates of PD (heterogeneity: Τ²=0.00; χ²=0.91; df=3; P=0.82; I²=0% and test for overall effect: Z=2.52; P=0.01) compared with the ICI alone group. Safety analysis revealed no significant difference between patients who received ICI + RT and those who received RT in terms of grade 1 or 2 AEs. In conclusion, the combination of ICIs + RT demonstrates promising efficacy and safety for patients with metastatic NSCLC. However, clinical trials that have tested this combination are lacking, which emphasizes the need for further research.