Pre-stereotactic radiosurgery neutrophil-to-lymphocyte ratio is a predictor of the prognosis for brain metastases

The neutrophil-to-lymphocyte ratio (NLR) has been reported to relate to the prognosis of various cancers. The aim of this study was to elucidate the efficiency of pre-treatment NLR as a predictor of outcomes of brain metastasis underwent gamma knife radiosurgery (GKRS). We analyzed 195 cases with brain metastasis underwent GKRS at our institution between January 2015 and April 2018. Patients’ clinical and radiographic data were collected. We identified 458 brain metastases in 195 patients. Optimal dichotomous cutoff values of NLR determined by receiver operating characteristic analysis for local control, distant control and overall survival (OS) were 2.48, 2.74 and 3.13, respectively. The actuarial local control rates of patients with high NLR were 87.4% at 6 months and 76.1% at 12 months, whereas that of patients with low NLR were 94.2% at 6 months and 88.3% at 12 months (P = 0.001). The actuarial distant control rates of patients with high NLR were 31.4% at 6 months and 18.9% at 12 months, whereas that of patients with low NLR were 58.5% at 6 months and 31.3% at 12 months (P = 0.001). The median OS of patients with high and low NLR were 10.0 months and 14.5 months, respectively (P = 0.001). Multivariate analysis demonstrates that high NLR independently predicts local failure (hazard ratio [HR], 2.281; P = 0.003), distant brain failure (HR 1.775; P = 0.002) and poorer overall survival (HR 1.494; P = 0.034). The pre-SRS NLR, a systemic inflammatory marker for treatment response, inversely predicts local control, distant control and OS in patients with brain metastasis.