PDCD1 and non-small cell lung carcinoma: Besides, current available studies on SBRT combined with PD-1/PD-L1 inhibitors are mostly limited to oligometastatic NSCLC (< 5 sites) while for NSCLC with limited metastases (> 5 sites), whether multisite SBRT or even all-site SBRT combined with PD-1/PD-L1 inhibitors could attain superior survival benefits remains to be explored clinically.