Thymidine kinase 1 (TK1) as a proteomic biomarker in cancer

Serum thymidine kinase 1 (TK1) is a notable biomarker of cellular increase that has well-determined diagnostic and prognostic uses in oncological laboratory medicine. This review examines the evolution of TK1 detection systems that now use enzyme-linked immunoassays rather than radioisotope-based activity assays to detect TK1, which are suitable for daily clinical chemistry laboratories. Modern dual-monoclonal ELISA systems have higher analytical capabilities, with a detection limit of 0.12 ng/mL and a precision coefficient of 5-15 % and a diagnostic sensitivity of 59-95 % in diverse malignancies. A cohort of over 15,000 patients has provided clinical evidence showing an important correlation between high levels of serum TK1 and tumor burden, disease stage, and treatment response in hematology and solid tumors. Comparative analyses revealed that combining TK1 with known biomarkers (CEA, CA19-9, and CYFRA21-1) increased the accuracy of diagnosis. This is especially so in multimarker panels, which have an range of 0.79-0.96 in AUC. The usefulness of TK1 as an early warning for cancer has been established in population screening in a study of more than 47, 000 individuals with a diagnostic accuracy of 96. TK1 has also been identified as a predictor of survival in other types of cancers through prognostic analyses. This is a systematic review of the high-quality results of 108 studies selected on the basis of a systematic search of the scientific databases of the most important literature, where specific attention was paid to the biochemical properties of thymidine kinase 1 and its use in cancer treatment. The main areas of implementation difficulty are assay standardization, platform-specific reference interval creation, and provision of quality assurance procedures. Further laboratory medical studies must be conducted to improve the uniformity of the tests, automation, and integration of automated systems into systematic testing to clarify the use of TK1 in precise cancer diagnosis.