Serum thymidine kinase 1 activity in breast cancer

Cancer Biomark. 2010;7(2):65-72. doi: 10.3233/CBM-2010-0148.


Aims: Thymidine kinase 1 (TK1) is an enzyme involved in DNA synthesis and an important proliferation marker. We explored the association of preoperative serum TK1 activity with clinicopathological parameters and prognosis in terms of recurrence-free survival (RFS) in breast cancer (BC) patients.

Patients and methods: TK1 activity in serum of 120 healthy women and 161 BC patients was measured by quantitative ELISA.

Results: Serum TK1 activity in BC patients was significantly higher than in healthy women (P < 0.0001). In BC patients elevated TK1 activity was significantly associated with advanced T stage (P = 0.015), higher grade (P = 0.013), presence of tumor necrosis (P = 0.006), vascular invasion (P = 0.002), and lack of estrogen receptor (ER) and progesterone receptor (PR) expression (P = 0.0004 and P = 0.003). Higher TK1 activity was found in patients with BRCA1/2 mutations compared to those without the mutation (P = 0.004). Multivariate Cox proportional hazards analyses demonstrated that TK1, adjusted for stage, grade, necrosis, ER and PR negativity was retained as an independent predictor of disease recurrence (Hazard Ratio = 3.9, 95%CI 1.3-11.6, P = 0.013).

Conclusion: Elevated serum TK1 is an important risk factor indicating a high proliferation potential of tumors at the time of excision. In multivariate analysis TK1 activity was found to be an independent prognostic factor for RFS.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Biomarkers, Tumor / blood
  • Breast Neoplasms / blood
  • Breast Neoplasms / enzymology*
  • Breast Neoplasms / pathology
  • Case-Control Studies
  • Disease-Free Survival
  • Female
  • Humans
  • Middle Aged
  • Neoplasm Recurrence, Local / pathology
  • Neoplasm Staging
  • Predictive Value of Tests
  • Prognosis
  • Prospective Studies
  • Receptors, Estrogen / metabolism
  • Receptors, Progesterone / metabolism
  • Risk Factors
  • Thymidine Kinase / blood*


  • Biomarkers, Tumor
  • Receptors, Estrogen
  • Receptors, Progesterone
  • Thymidine Kinase
  • thymidine kinase 1