PT  - JOURNAL ARTICLE
AU  - Eberlein, Uta
AU  - Scherthan, Harry
AU  - Bluemel, Christina
AU  - Peper, Michel
AU  - Lapa, Constantin
AU  - Buck, Andreas Konrad
AU  - Port, Matthias
AU  - Lassmann, Michael
TI  - DNA Damage in Peripheral Blood Lymphocytes of Thyroid Cancer Patients After Radioiodine Therapy
AID  - 10.2967/jnumed.115.164814
DP  - 2016 Feb 01
TA  - Journal of Nuclear Medicine
PG  - 173--179
VI  - 57
IP  - 2
4099  - http://jnm.snmjournals.org/content/57/2/173.short
4100  - http://jnm.snmjournals.org/content/57/2/173.full
SO  - J Nucl Med2016 Feb 01; 57
AB  - The aim of the study was to investigate DNA double-strand break (DSB) formation and its correlation to the absorbed dose to the blood in patients with surgically treated differentiated thyroid cancer undergoing their first radioiodine therapy for remnant ablation. Methods: Twenty patients were included in this study. At least 7 peripheral blood samples were obtained before and between 0.5 and 120 h after administration of radioiodine. From the time–activity curves of the blood and the whole body, residence times for the blood self-irradiation and the irradiation from the whole body were determined. Peripheral blood lymphocytes were isolated, ethanol-fixed, and subjected to immunofluorescence staining for colocalizing γ-H2AX/53BP1 DSB-marking foci. The average number of DSB foci per cell per patient sample was analyzed as a function of the absorbed dose to the blood and compared with an in vitro calibration curve for 131I and 177Lu established previously in our institution. Results: The average number of radiation-induced foci (RIF) per cell increased over the first 3 h after radionuclide administration and decreased thereafter. A linear fit from 0 to 2 h as a function of the absorbed dose to the blood agreed with our in vitro calibration curve. At later time points, RIF numbers diminished, along with dropping dose rates, indicating progression of DNA repair. Individual patient data were characterized by a linear dose-dependent increase and a biexponential response function describing a fast and a slow repair component. Conclusion: With the experimental results and model calculations presented in this work, a dose–response relationship is demonstrated, and an analytic function describing the time course of the in vivo damage response after internal irradiation of patients with 131I is established.