title: Clinicopathological and prognostic value of programmed death ligand-1 (PD-L1) in renal cell carcinoma: a meta-analysis.
abstract: BACKGROUND
  Recently, the association of immunological checkpoint marker programmed death ligand-1 (PD-L1) and the prognosis of various cancers has always been a research hotspot. The objective of this study is to assess the clinical value of PD-L1 as a novel prognostic biomarker of renal cell carcinoma (RCC).
  
  
  METHODS
  Medline/PubMed, EMBASE, the Cochrane Library databases and Grey literature were searched up to 30 March 2015 for eligible studies of the association between PD-L1 expression and cancer-specific survival (CSS) in RCC. The risk ratio (RR) and its 95% confidence interval (CI) were calculated from the included studies. Moreover, the odds ratio (OR) was also extracted to evaluate the association between the clinicopathological parameters of participants and PDL1 expression.
  
  
  RESULTS
  Five studies involving 1073 patients were included in the meta-analysis. The pooled results showed that positive/higher PD-L1 expression was a negative predictor for CSS with RR of 2.90 (95% CI: 1.64-5.13; Pheterogeneity. ≤ 0.001). Additionally, increased PD-L1 was found to be significantly associated with large tumor size (OR = 2.28, 95% CI: 1.61-3.23; Pheterogeneity. = 0.645), high TNM stage (OR = 4.37, 95% CI: 2.99-6.39; Pheterogeneity. = 0.676), poor nuclear grade (OR = 7.58, 95% CI: 5.26-10.92; Pheterogeneity. = 0.203) and present tumor necrosis (OR = 6.77, 95% CI: 4.73-9.71; Pheterogeneity. = 0.111) in renal cell carcinoma patients.
  
  
  CONCLUSIONS
  The meta-analysis suggested that PD-L1 could act as a significant biomarker in the worse prognosis and adverse clinicopathologic features of renal cell carcinoma.
authors.affiliation: Department of General Surgery, Beijing Chao-Yang Hospital, Capital Medical University Beijing 100020, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.affiliation: Department of Oncology, Beijing Chao-Yang Hospital, Capital Medical University Beijing 100020, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Oncology, Beijing Chao-Yang Hospital, Capital Medical University Beijing 100020, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Oncology, Beijing Chao-Yang Hospital, Capital Medical University Beijing 100020, China.
authors.forename: Guangyu
authors.initials: G
authors.lastname: An
authors.affiliation: Department of General Surgery, Beijing Chao-Yang Hospital, Capital Medical University Beijing 100020, China.
authors.forename: Guosheng
authors.initials: G
authors.lastname: Feng
authors.affiliation: Department of Oncology, Beijing Chao-Yang Hospital, Capital Medical University Beijing 100020, China.
authors.forename: Fuquan
authors.initials: F
authors.lastname: Liu
keywords: PD-L1; meta-analysis; prognosis; renal cell carcinoma