Predictive factors of cytotoxic damage in radioactive iodine treatment of differentiated thyroid cancer patients

Radioactive iodine ( 131 I) therapy in patients suffering from differentiated thyroid cancer (DTC) is a targeted treatment commonly used for thyroid ablation and locoregional and distant metastatic spread management. Despite a significant proportion of the 131 I dose entering the circulation, there is currently no detailed information regarding its effect on the blood cell system. In order to assess the cytotoxic effects of 131 I therapy on the circulatory system, blood cell levels, thyroid-related hormones and CD45 + cell cytotoxicity were estimated in blood collected from patients with DTC. The micronuclei (MN) frequency of the peripheral blood CD45 + cell fraction was significantly increased after 30 days of 131 I therapy compared to that prior to treatment, although a strong individual variation was observed. A significantly negative correlation between MN frequency and the level of platelets and plateletcrit was observed; however, there was no such correlation with thyroid-related hormones. These resultS suggest that the correlation between MN frequency and the platelet system may serve as a biomarker of exposure and, possibly, of sensitivity in DTC patients undergoing 131 I therapy following thyroid and lymph node surgery.