Serum Thymidine Kinase 1 - Potential Prostate Cancer Biomarker: A Clinical Study.

Background/aim: Serum thymidine kinase 1 (STK1) is a proliferation biomarker that has been used as a diagnostic marker of several malignant diseases. However, there are limited data for prostate cancer (PCa).

Patients And Methods: In this study, we retrospectively analysed serum samples from 169 patients with biopsy confirmed PCa, who had been indicated for radical prostatectomy (RP) between 2013-2016. The results were compared with those in serum samples from 39 healthy men. We used commercially available enzymatic immunoassay to determine the levels of STK1. The patients were divided into groups according to the Gleason score (GS) and risk factors for adjuvant radiotherapy (aRT), which were defined as GS 8-10, pT3, and a positive surgical margin.

Results: The median serum level of STK1 in PCa patients was 0.289 pmol/l. In the control group, the median value was 0.0116 pmol/l (p<0.001). By comparing the patients with GS≤6 vs. 7 vs. ≥8 (p=0.01), we found statistically significant differences. In the correlation of STK1 values with risk factors, we found statistically significant differences both in comparison of 0 vs. 1 vs. 2 vs. 3 risk factors (p=0.021), as well as ≤1 vs. 2≥ risk factors (p=0.009).

Conclusion: The levels of STK1 are significantly higher in patients with PCa than those in healthy controls. Furthermore, STK1 values correlate with GS and predefined risk factors for aRT. Therefore, STK1 can be considered as a potential tumour marker of PCa diagnosis and risk stratification.