Investigation of DNA damage by the alkaline comet assay in 131I-treated thyroid cancer patients.

OBJECTIVE: To assess the possible applicability of comet assay in the evaluation of DNA damage caused by ionizing radiation. The alkaline comet assay or single-cell gel electrophoresis has been used as a standard method for measuring and analyzing DNA damage. STUDY DESIGN: Peripheral blood samples were collected from papillary thyroid cancer patients who received 131I by oral administration. Blood samples were taken just before the treatment, on the first day of treatment, and 1 week posttreatment. To determine the radiation-induced DNA damage, alkaline comet assay was performed. RESULTS: It was found that significantly high levels of DNA damage occurred in first day samples when compared to control samples according to tail moment measurements. Also, a decrease in the level of damage was observed in the 1-week samples. CONCLUSION: Our observations and data confirmed that treatment with 131I for papilloma thyroid cancer can cause DNA damage in circulating lymphocytes, and the comet assay seemed suitable to assess the effect of radioactive iodine for the patients.