Can Thymidine Kinase Levels in Breast Tumors Predict Disease Recurrence?
Background: Our previous study of thymidine kinase (TK) levels in the serum of breast cancer patients demonstrated a statistically significant positive correlation with cancer stage. In postsurgical follow-up studies of 20 patients with primary breast cancer, total serum TK levels rose with disease recurrence and continued to rise with disease progression but decreased with treatment response. Purpose: This study was designed to examine whether TK levels in primary breast tumors can be used to predict recurrence and to establish the relationship between TK levels and estrogen receptor (ER) status and recurrence. Methods: Eighty-six patients with breast cancer were entered in this study. Tumors were assessed for ER status and TK levels, and the patients had follow-up for recurrence over a period of 41 months. By calculating the percent of TK activity in the presence of adenosine triphosphate (ATP) or cytidine triphosphate (CTP), we estimated the relative contributions of TK isozymes TK1
