A Novel Risk Assessment Method Using Pretreatment Neutrophil-to-Lymphocyte and Platelet-to-Lymphocyte Rates for Early-Stage Non-Small-Cell Lung Cancer Treated with Stereotactic Body Radiation Therapy

Abstract

The index of systemic inflammation, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are associated with clinical outcomes for many types of carcinomas. We aimed to assess the impact of pretreatment NLR and PLR on long-term prognosis of early-stage non-small-cell lung cancer (NSCLC) treated with stereotactic body radiation therapy (SBRT), and introduce a novel risk assessment method. We designed a single-center retrospective cohort study on patients underwent SBRT for early-stage NSCLC between 2004 and 2016. Data acquisition was through medical records, blood count recorded within 1-week before SBRT were selected to calculate the pretreatment NLR and PLR. Patients were divided into three subgroups according to median NLR (NRLm) and median PLR (PLRm). a) high risk group: ≥NRLm and ≥PLRm; b) intermediate risk group: < NRLm and ≥ PLRm, or ≥ NRLm and < PLRm; c) low risk group: < NRLm and < PLRm. Overall survival (OS) were calculated using the Kaplan-Meier method from the first day of treatment, and evaluated by the log-rank test. Cox proportional hazards model were used for univariate analyses. A total of 111 patients were included in this study. The median duration of follow-up for all patients was 42 (range from 3 to 105) months. 51 deaths were observed, and the 3-year OS and CSS for all patients were 70.1% and 83.3%, respectively. The median and range of the NLR and PLR were 2.28 (0.89-13.77) and 140.00 (51.12-568.57) respectively. High risk group patients showed a median OS of 48.2 months. In contrast, intermediate risk group and low risk group patients had a median OS of 63.4 and 68.7 months, respectively (p = 0.045). In univariate analysis, risk group, gender, histological tumor type, T-stage, and PLRm were associated with OS. Risk group and T-stage were associated with CSS. In multivariable analysis, Lower T-stage and PLR were found to be associated with higher OS. Only T-stage was significantly associated with CSS. NRLm was not independently associated with OS or CSS. We invented a novel risk assessment method using a combination of NLR and PLR, which could potentially provide a simple and inexpensive methodology for predicting the long-term survival in patients of early-stage NSCLC treated with SBRT.