Thymidine Kinase 1 in Serum Predicts Increased Risk of Distant or Loco-regional Recurrence Following Surgery in Patients with Early Breast Cancer

Background: The prognostic value of the concentration of serum thymidine kinase 1 (S-TK1) with regard to recurrence in low risk breast cancer patients, 3 months after surgery was evaluated. Patients and Methods: The concentration of S-TK1 in serum was determined in 120 breast cancer patients at the time of surgery and in 67 patients 3 months after surgery, by anti-TK1 chicken IgYantibody, using a dot-blot immuno-assay. The S-TK1 concentration was compared with the serological activity of thymidine kinase (STK) and of carbohydrate antigen (CA 15-3). Results: A statistically significant trend (unadjusted) was found for recurrence (distant or loco-regional) in patients with a higher S-TK1 concentration, as compared with patients with a lower S-TK1 concentration. A multivariate analysis gave the same results. The hazard rate ratio for developing distant and/or loco-regional recurrence in patients with a higher S-TK1 concentration was about six to seven times higher than in patients with a lower S-TK1 concentration. Conclusion: Our results indicate that the S-TK1 concentration is higher in patients developing distant and/or loco-regional recurrence 3 months post-surgery.