Clinical applicability of the proliferation marker thymidine kinase 1 in head and neck cancer patients

Background/Aim: Prognostic factors serve as a vital tool in the treatment of patients with head and neck cancer (HNC). The aim of this study was to evaluate the clinical potential of Thymidine-kinase-1 (TK1) marker in the prognosis of HNC patients. Patients and Methods: We evaluated 366 blood samples from 278 HNC patients and 88 healthy controls, using an ELISA assay. Correlations of TK1 levels with disease stage, lymph node involvement and response to radiation therapy, were determined. Results: In HNC patients, TK1 levels were significantly higher compared to healthy controls. Significantly higher TK1 levels were demonstrated in node positive cases and in advanced disease stages compared to node negative and early disease stages. Levels were higher prior to radiation and decreased significantly thereafter, in patients responding to treatment. Increasing levels of TK1 post-radiation were indicative of recurrence or of non-response to treatment, while decreasing levels indicated a positive response. Conclusion: TK1 is a tumor marker in HNC patients with the ability to assess response to therapy. High or increasing levels correlated to a poor prognosis, whereas low levels correlated to an overall increased survival.