SLC6A1 and prostate cancer: Further univariate analysis using a COX regression model revealed that SLC6A1 expression (P = 0.005, Table 2), Gleason score (P = 0.0001, Table 2), pathological tumor stage (P = 0.0001, Table 2) and clinical stage (P = 0.001, Table 2) were significantly associated with metastasis-free of prostate cancer patients.