THYMIDINE KINASE AS A PARAMETER FOR THE DETERMINATION OF TUMOR-ACTIVITY OF MALIGNOMA UNDER RADIATION-THERAPY

Background: The influence of irradiation on the tumor marker thymidine kinase in patients with malignant disease was investigated. Patients and Methods: Serum thymidine kinase (S-TK) was determined in 31 patien ts with histologically proven malignant disease before, during and aft er radiation therapy. 16 patients had malignant lymphoma, 10 ENT tumor s and 5 prostate carcinomas. Results were compared with data from 56 t umor patients, who were clinically in complete remission. Results: In 38% of the irradiated patients and in 18% of the control patients in c omplete remission S-TK was elevated (<5 U/l). Differences were not sta tistically significant, as were differences before and after radiation therapy in the study group. Conclusions: Although a significant incre ase in S-TK in the 1st week and a fall during the 2nd week of treatmen t in malignant lymphoma patients could be observed, S-TK determination s after completion of radiation therapy do not appear to be an indicat or of complete tumor elimination or of residual tumor. However, in mal ignant lymphoma the level of S-TK and its decline under radiation trea tment seem to be a prognostic factor for response to therapy.