Association Between ABO Blood Group and Survival Outcomes in Advanced NSCLC Treated with Immune Checkpoint Inhibitors

Background: Reliable biomarkers that predict outcomes with immune checkpoint inhibitors (ICIs) in non-small cell lung cancer (NSCLC) remain limited. ABO blood group antigens may influence tumor immunity and response to immunotherapy. Methods: We retrospectively analyzed 239 patients with advanced NSCLC treated with ICI-based therapy between 2019 and 2024. Patients were classified according to ABO blood group, and overall survival (OS), progression-free survival (PFS), and treatment response were evaluated. Results: Patients with blood group O had significantly longer OS (18.6 vs. 11.0 months; p < 0.001) and PFS (9.4 vs. 4.2 months; p = 0.001) than patients with non-O blood groups. In multivariable analyses, blood group O remained independently associated with improved OS and PFS. Conclusions: Blood group O may represent a simple and readily available host-related prognostic marker in patients with advanced NSCLC receiving ICI-based therapy. Prospective multicenter studies are required to validate these findings.