Improved survival with SBRT plus PD-1/PD-L1 inhibitors in lung metastases patients: A propensity score-matched study

This study compares stereotactic body radiotherapy (SBRT) alone versus SBRT combined with immunotherapy (SBRT+IT) for pulmonary metastases. In a retrospective analysis of patients from Sir Run Run Shaw Hospital, cohorts were balanced using propensity score matching. While local control was similar between groups, the SBRT+IT group demonstrated a significantly superior median overall survival (51.3 vs. 35.5 months, P < 0.05), indicating a systemic benefit from immunotherapy. Multivariable analysis identified C-reactive protein (CRP), the CRP-to-albumin ratio (CAR), and the CRP-to-lymphocyte ratio (CLR) as independent prognostic factors for SBRT+IT outcomes, with low baseline levels predicting longer survival. The receiver operating characteristic analysis demonstrated three markers possessed good to excellent predictive ability for short-term survival. We conclude that combining SBRT with immunotherapy significantly improves survival compared to SBRT alone, primarily through systemic immune activation rather than enhanced local tumor control. Furthermore, CRP, CAR, and CLR serve as robust prognostic biomarkers for this combination strategy, highlighting the clinical value of this synergistic approach for improving the prognosis of patients with lung metastases.