Strategy Integrating Stereotactic Body Radiation Therapy with Immune Checkpoint Inhibitors for Oligometastatic Non-Small Cell Lung Cancer: A Narrative Review

The therapeutic approach for oligometastatic non-small cell lung cancer (NSCLC) is rapidly shifting from palliative care to curative-intent strategies. This shift is largely driven by the integration of immune checkpoint inhibitors (ICIs) and stereotactic body radiation therapy (SBRT). SBRT functions biologically as an "in situ vaccine," inducing immunogenic cell death and activating the cGAS-STING pathway to enhance systemic anti-tumor immunity, whereas ICIs may help sustain this radiation-primed immune response. Randomized phase II trials and pooled analyses have suggested the potential clinical benefit of adding radiation to ICIs, particularly in tumors with low or absent PD-L1 expression. However, the phase II/III NRG-LU002 trial found no improvement in progression-free or overall survival with the addition of local consolidative therapy to maintenance systemic therapy, indicating that the incremental benefit of local therapy may be limited in patients already deriving effective disease control from contemporary systemic regimens. Retrospective studies, including those utilizing recursive partitioning analysis and PD-L1-based stratification, have proposed a "risk-based" approach in which patients with an intermediate metastatic burden and low PD-L1 expression may derive greater benefit; these observations remain hypothesis-generating and require prospective validation. Looking ahead, the field is moving towards precision radio-immunotherapy, in which molecular biomarkers and rationally designed dose-fractionation and sequencing strategies are aimed at improving clinical outcomes while minimizing toxicity for patients with oligometastatic NSCLC.