Purpose: The purpose of our study was to evaluate the degree of radiotoxicity to lymphocytes in thyroid cancer after iodine-131(I-131) therapy using γ-H2AX foci immunodetection.
Methods: This study focused on 15 patients who underwent I-131 therapy for differentiated thyroid cancer after surgery. All patients received 3.7 GBq of I-131. Venous blood samples were collected from each patient before therapy and 4 days thereafter. Lymphocytes were isolated from the blood samples and subjected to γ-H2AX immunofluorescence staining.
Results: The number (mean ± SD) of foci per lymphocyte nucleus was 0.41 ± 0.51 before and 6.19 ± 1.80 after radioiodine therapy, and this difference was statistically significant (P = 0.001 < 0.05). Absorbed doses estimated for the 15 patients were 0.77 ± 0.31 Gy applying standard line in vitro external radiation doses.
Conclusion: γ-H2AX foci immunodetection in lymphocytes may detect radiation-induced DNA damage associated with I-131 therapy for thyroid cancer, and may facilitate estimation of the radiation doses absorbed with this therapy.