Background/aim: Thymidine kinase 1 (TK1) is involved in DNA synthesis and is considered a reliable and sensitive marker of cell proliferation. The aim of this study was to investigate the prognostic value of measurements of serum TK1 activity following tumor ablation.
Patients and methods: This study was performed on 32 patients with renal cell carcinoma (RCC) who had undergone nephrectomy and 35 patients with cancer of different histology with metastases to the liver (n=28) and lung (n=7) treated with radiofrequency ablation (RFA). The TK1 activity was measured with DiviTum (Biovica) immunoassay.
Results: In patients with RCC with no evidence of disease during their observation, a significant decrease of the TK1 activity was observed on the day following nephrectomy (p<0.0001). The mean calculated half-life ±SEM was 10.8±1.2 h. Taking into account the short half-life, measurements of TK1 were performed 24 h after nephrectomy or RFA of metastases. It was found that elevated TK1 activity (>60 Du/l) on the day after nephrectomy independently predicted poor recurrence-free survival (hazard ratio=5.0, p=0.040), after adjustment for T-stage, age and pretreatment TK1. Patients scheduled for RFA averaged 1.4 lesions and an average lesion diameter of 2.2 cm. Multivariate Cox's regression model demonstrated the significant association of any increase of TK1 activity or decrease not reaching ≤60 Du/l on the day after ablation with poor progression-free survival (hazard ratio=4.6, p=0.001), after adjustment for the type of primary tumor, the number and size of metastases.
Conclusion: The half-life for serum TK1 activity is 10.8±1.2 h. The measurements of TK1 activity following nephrectomy or RFA of metastases could be an important tool in prognostic evaluation.
Keywords: TK1 activity; half-life; nephrectomy; prognosis; radiofrequency ablation.
Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.