Peripheral blood eosinophil count for predicting progression-free survival in non-small cell lung cancer: A retrospective cohort study

Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related death globally. Immune checkpoint inhibitors improve outcomes but benefit only a subset of patients. Peripheral blood eosinophil count (PBEC) is a potential predictive biomarker, yet its role in progression-free survival (PFS) remains underexplored. This retrospective study enrolled 121 stage III/IV NSCLC patients treated with immune checkpoint inhibitors at Anqing Medical Center from 2019 to 2024. Baseline and posttreatment PBEC were analyzed with clinical variables. Kaplan-Meier, log-rank test and Cox regression were used for PFS prognosis; univariate logistic regression, Akaike Information Criterion stepwise selection and nested cross-validation were applied for model exploration. Multivariate Cox regression identified baseline Log(PBEC) as an independent protective factor for PFS (hazard ratio = 0.58, 95% CI: 0.36-0.94, P = .026), with higher PBEC linked to longer PFS. Five independent predictors were screened: sex, liver metastasis, performance status score, anti-angiogenic therapy and Log(PBEC). The exploratory model showed stable performance and clinical net benefit. Baseline PBEC is a potential and accessible predictor of PFS in NSCLC patients. A nomogram incorporating PBEC and clinical factors provides preliminary support for prognostic assessment and requires prospective validation before clinical application.