Immunotherapy With Anti-PD-1 Versus Anti-PD-L1 in SCLC: A Comprehensive Retrospective Analysis.

Small cell lung cancer (SCLC) is a highly malignant tumor characterized by strong invasiveness and poor prognosis. Immune checkpoint inhibitors have provided new therapeutic options for SCLC, but their comparative clinical benefit remains unclear. This retrospective study enrolled 171 patients with SCLC treated between January 2016 and June 2023, with follow-up through June 30, 2024, to compare survival and safety profiles between anti-programmed death-1 (anti-PD-1) and anti-programmed death-ligand 1 (anti-PD-L1) inhibitors. Among the 119 patients (69.6%) who received immunotherapy plus chemoradiotherapy, the median overall survival (OS) was 48.3 months, compared with 25.2 months in those who did not receive radiotherapy. Multivariable Cox regression confirmed that liver metastasis and radiotherapy status were independently associated with OS and progression-free survival (PFS). Subgroup analyses revealed that patients younger than 65 years who underwent radiotherapy, particularly those without liver metastasis, achieved longer OS with anti-PD-1 agents. In conclusion, both anti-PD-1 and anti-PD-L1 inhibitors improved the prognosis of SCLC. Patients younger than 65 years receiving radiotherapy and those with limited-stage SCLC may represent populations more likely to benefit from anti-PD-1 therapy.