Thymidine Kinase-1 as Additional Diagnostic Marker of Prostate Cancer

Background: Thymidine kinase-1 (TK-1) is associated with proliferation and malignancy and has been extensively studied as a diagnostic biomarker for a variety of tumors, but there are limited data for prostate cancer. Methods: TK-1 concentrations in serum were measured in 59 patients with prostate cancer (mean age 68 years) and in the control group of 28 healthy men (mean age 63 years) using commercially available enzymatic immunoassay (LSBio, Inc., Seattle, WA, USA). The patients were divided with respect to the severity of the disease into two groups according to the European Association of Urology (EAU) guidelines (Stage 1, 2 - less severe tumors, stage 3 - severe tumors). Results: Serum thymidine kinase-1 concentrations were significantly elevated in the group of the patients with prostate cancer compared to the healthy individuals (0.204 pmol/L vs. 0.072 pmol/L, with p < 0.0001). Diagnostic efficiency of serum TK-1 concentrations was 0.792 with the specificity of 53.6% and sensitivity of 94.9%. Patients with less severe tumors (Stage 1, 2) and severe tumors (Stage 3) had significantly increased levels of TK-1 as well (p < 0.0001). Combination of TK-1 and PSA investigation in patients with PCa improve the diagnostic validity of TK-1 (AUC = 0.87). Conclusions: Concentrations of thymidine kinase 1 are increased in all patients with prostate cancer and even more in patients with severe prostate cancer. Thymidine kinase 1 appears to be a promising additional diagnostic marker promising in patients with prostate cancer.