Herein, our study aimed to retrospectively assess the PD-1/PD-L1 expression status in prostate cancer and BPH tissue by immunohistochemistry, as well as the association between PD-1/PD-L1 and related clinicopathological parameters including age, PSA, Gleason score, lymph node metastasis, clinical T stage and risk factor grade. The gene discussed is KLK3; the disease is Familial prostate cancer.