Inflammation index predicts radiation-induced lung injury and prognosis in lung tumors treated with stereotactic body radiation therapy

Purpose To investigate the effect of inflammation-based indexes in predicting radiation pneumonitis (RP) and prognosis in lung tumor patients treated with stereotactic body radiation therapy (SBRT). Materials and methods The data of one hundred and seventy-two patients with 272 lung lesions from November 2015 to December 2020 were retrospectively analyzed. Pretreatment hematological indexes including platelet count, neutrophil count, and lymphocyte count were collected before treatment. Systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) were calculated. The receiver operating characteristic (ROC) curve was established to predict the RP and overall survival of patients, and the Youden index was calculated to determine the cutoff values of SII, NLR, and PLR before radiotherapy. Results Pretreatment SII, NLR, and PLR could predict RP in lung tumor patients treated with SBRT, the optimal cutoff values of SII, NLR, and PLR were 355.38, 2.04, and 141.09, respectively. Pretreatment PLR could predict survival and the optimal cutoff value of PLR was 166.83, patients with a PLR > 166.83 predict worse overall survival (OS) ( P 166.83 were 82.0% and 58.5%, respectively. Conclusion In lung tumor patients treated with SBRT, pretreatment SII, NLR, and PLR can effectively predict RP and a higher PLR predicts poor OS. These inflammation-based indexes could serve as reliable and convenient predictors to guide treatment for physicians in clinical practice.