PD-L1 Expression in Japanese Renal Cell Carcinoma Patients

Inclusion Criteria: * 1\. Written informed consent for this study. In the case obtaining written informed consent is difficult due to death, change of address, and so on, the opt-out consent is accepted by giving patients or their relatives notification regarding the usage of their clinical information and surgical samples for the research. * 2\. Age at nephrectomy≧20 years * 3.Patients with recurrent or metastatic RCC who have initiated first line treatment between 1 January 2010 and 31 December 2015, with representative FFPE of nephrectomy surgical specimen which are suitable for assessment of PD-L1 expression Exclusion Criteria: * 1\. Malignancies other than RCC is co-existed from the time of nephrectomy and death. * 2\. Treatment with anti-CTLA-4 antibody, anti-PD-1/PD-L1 antibodies as first-line therapy for recurrent or metastatic RCC.