An evaluation of thymidine kinase as a potential tumour marker in bladder cancer
Transitional Cell Carcinoma (TCC), the commonest primary lesion to affect the human bladder, has an unusual and unexplained distribution within the bladder. In a small study of patients with bladder TCC, TK was significantly elevated only in the mononuclear leukocytes. This suggested the potential of mononuclear leukocyte TK as a tumour marker for TCC of the bladder. Most primary TCCs occur on the bladder base, so a relative deficiency of TK in this area could offer a possible explanation for this tumour distribution. Both total TK and TK1 activities were significantly lower in the mucosa of the bladder base compared to that of the dome in 32 controls. No significant differences were detected in either total TK or TK1 activities between the control group (n=37) and the tumour group (n=43, 30, 39 respectively) for either serum, mononuclear leukocytes or urine. Furthermore there was no correlation between any of these parameters and time, treatment or recurrence. TK activity in normal bladder mucosa in the tumour population was increased at all sites compared with control bladder mucosa. The significant decrease in total TK in the mucosa of the bladder base was, however, maintained. TK activity in serum, mononuclear leukocytes and urine has no potential as a tumour marker for TCC of the bladder and bears no temporal relationship to tumour management or recurrence. The significant decrease in TK activity in the mucosa of the bladder base offers a possible explanation for the increased incidence of primary TCC occurring in that site. TK activity in tumour tissue gives no indication of the risk of recurrence.