PECULIARITIES OF LYMPHOCYTE DNA SYNTHESIS IN THYROID CANCER PATIENTS UNDER CONDITIONS OF RADIOIODINE THERAPY

Zamotayeva G.A., Stepura N.M., Goidash M.M., Tronko M.D.

The authors present the results of a study of general and reparative synthesis of DNA in peripheral blood lymphocytes in 127 patients with differentiated thyroid cancer, having received therapeutic (4130–4730 MBq) and diagnostic doses (70–80 MBq) of iodine-131, and in 36 donors. It has been established that radioiodine led to a decrease in general DNA synthesis and an increase in reparative DNA synthesis in patients’ lymphocytes. Reparative DNA synthesis reached maximal values on day 7 and remained significantly elevated at least within 6 months after isotope administration. For all periods of follow-up, the indices of reparative synthesis after administration of therapeutic doses of radioiodine were higher compared to diagnostic scintigraphy. In the group of patients with distant metastases who received several courses of radioiodine therapy, the baseline level of reparative DNA synthesis exceeded by 25% the same indicator in patients without metastases. Thus, the data obtained suggest that peripheral blood irradiation under conditions of radioiodine therapy appears to be sufficient to induce long-term radiation injury of DNA in lymphocytes. Further investigations are needed for a grounded estimation of immuno-hematological after-effects of radioiodine, for determining their degree and duration.