Prognostic value of pretreatment neutrophil count in metastatic renal cell carcinoma: a systematic review and meta-analysis

Background: In recent years, inflammation has become widely recognized as a crucial component in tumor development and progression. Neutrophils are one of the most common inflammatory markers during hematological examinations. The prognostic value of neutrophils in metastatic renal cell carcinoma (mRCC) remains inconsistent. The aim of this meta-analysis is to evaluate the prognostic value of pretreatment neutrophil count in patients with mRCC. Methods: PubMed, Web of Science and Embase were searched for data on the association between pretreatment neutrophil count and mRCC prognosis up to October 7, 2017. We sorted out relevant studies and extracted the hazard ratio (HR) and its 95% confidence interval (CI) for overall survival (OS) and progression-free survival (PFS). Results: A total of 13 studies containing 3,021 patients with mRCC were summarized in the present meta-analysis. An elevated pretreatment neutrophil count yielded a worse OS (HR=2.17, 95% CI=1.68-2.79, P<0.001) and PFS (HR=1.78, 95% CI=0.91-3.49, P<0.001). Furthermore, we performed a subgroup analysis based on cut-off value, ethnicity, treatment method and analysis type. As a result, the association between pretreatment neutrophil count and survival was statistically significant in the subgroups of cut-off value, ethnicity, treatment method and analysis type. Conclusion: Our results show that the pretreatment neutrophil count is associated with mRCC outcomes and can be used as a valuable inflammatory marker for prognosis monitoring.