SERUM THYMIDINE KINASE LEVELS ARE ELEVATED AND EXHIBIT DIURNAL-VARIATIONS IN PATIENTS WITH ADVANCED OVARIAN-CANCER

Deoxythymidine kinase (TK) is an enzyme involved in DNA synthesis whos e serum activity reflects the proliferative activity of tumors and cor relates with prognosis in various malignancies. In ovarian cancer, the value of s-TK has not been studied so far. Therefore the serum levels of TK were investigated in patients with advanced ovarian cancer. Bec ause considerable diurnal fluctuations of s-TK levels were reported pr eviously, repeated determinations were performed over a 48-h time span . Fourteen patients (mean age+/-S.D., 56.1+/-8.0 years) with advanced ovarian cancer and five healthy volunteers (30.2+/-3.5 years) were stu died. Serial determinations of s-TK and serum CA 125 (s-CA 125) levels were performed over a 48-h time period. S-TK and s-CA 125 were elevat ed (> 4.7 U/l and > 35 U/ml) in 10 patients at least once over the 48- h period, respectively. Linear regression analysis showed a strong cor relation between s-TK and s-CA 125. However, three patients with consi stently normal s-CA 125 values (less than or equal to 35 U/ml) had ele vated s-TK levels, indicating that these two parameters may be indepen dent in some patients. Both s-TK and s-CA 125 levels showed considerab le diurnal changes over the 24-h period in individual patients, in mar ked contrast to normal subjects. Individual peak-trough differences ra nged from 0.1-8.5 U/l or 5-268% for s-TK, and from 4-75 U/ml or 15-100 % for s-CA 125. Peak-trough differences of s-TK greater than or equal to 100% were found in five patients. The circadian fluctuations of s-T K and CA 125 did not show a regular circadian pattern nor any temporal covariation. This study demonstrates for the first time that s-TK lev els may be elevated in ovarian cancer. In some patients, s-TK levels m ay exhibit considerable, irregular diurnal fluctuations. Repeated dete rminations should therefore be performed in situations where this mark er is relevant for patient monitoring. (C) 1997 Elsevier Science B.V.