Abstract: ObjectiveTo explore the prognostic value of prechemotherapy serum cystatin C (Cys C) in patients with castrationresistant prostate cancer (CRPC). MethodsThe medical records of 48 patients with CRPC were reviewed. These patients were diagnosed and underwent docetaxelbased chemotherapy in Xinjiang Military Command General Hospital between January 2009 and January 2015. Statistical analysis was performed to identify the clinical and prognosis value of Cys C. ResultsOf 48 patients with CRPC, the expression of serum Cys C before chemotherapy was related with Gleason score (χ2=4.218, P=0.040) and distant metastasis(χ2=4.090, P=0.043). 23 patients was in high group (Cys C＞1.61 mg/L), 25 in low (Cys C≤1.61 mg/L). The median survival time of high group and low group were 15.6 and 25.3 months, respectively (χ2=13.876, P＜0.001). Univariate analysis showed that TNM stage (χ2=6.934, P=0.018), Gleason score (χ2=7.933, P=0.005), baseline prostate specific antigen (PSA) (χ2=9.038, P=0.003), number of chemotherapy cycles (χ2=5.024, P=0.028), distant metastases (χ2=6.963, P=0.013) and serum Cys C before chemotherapy (χ2=6.976, P=0.012) were associated with overall survival of patients with CRPC. COX multivariate analysis showed that baseline PSA at diagnosis (χ2=4.257, P=0.039), number of chemotherapy cycles (χ2=6.245, P=0.017), distant metastases (χ2=5.122, P=0.028) and serum Cys C before chemotherapy (χ2=8.172, P=0.004) were independent risk factors of overall survival of patients with CRPC, especially serum Cys C before chemotherapy (HR=2.394). ConclusionThe patients with high Cys C level have poor prognosis, and the prechemotherapy Cys C is an independent risk factor for prognosis of CRPC patients treated with docetaxelbased chemotherapy which can be used as an effective indicator to assess the prognosis of CRPC.

Key words: Prostatic neoplasms, Prognosis, Drug therapy, Cystatin C