Oncología (Barcelona)
ISSN 0378-4835
NAVARRO FERNANDEZ, J. et al. Actividad genotóxica de la terapia con I131 en pacientes tratados por carcinomas de tiroides. []. , 27, 1, pp.40-48. ISSN 0378-4835.
INTRODUCTION: The micronuclei (MN) test of irradiated human lymphocytes with cytogenetic arrest (LCA) is employed to evaluate the chromosomal damage and the genotoxic effect of different physical and chemical agents. OBJECTIVE: To determine the possible genotoxic effect induced by I131 therapy of thyroid cancer patients, and to calculate the equivalent total body irradiation (TBI) of the treatment. MATERIAL AND METHODS: The frequency of appearance of MN was determined in LCA cultures from three different groups: 1) 35 healthy volunteers, in order to establish the spontaneous frequency of MN; 2) 9 supposedly healthy volunteers to carry out in vitro dose-response curves of gamma rays irradiated lymphocytes, and 3) 25 patients with thyroid carcinoma that had received ablative doses of I131 to treat the disease. The number of MN per 500 LCB before the treatment and three days after the administration of I131 was determined. The equivalent TBI of the therapy was assessed by comparing the frequency of MN in lymphocytes obtained three days after the I131 administration with the dose of gamma radiation necessary to produce the same frequency of MN in in vitro irradiated lymphocytes from healthy people. RESULTS: A lineal relationship was found between the frequency of MN and the dose of gamma radiation in vitro. The MN frequency of the lymphocytes after the I131 treatment was 8.89 MN per 500 LCA, a significantly higher figure doubling the spontaneous basal frequency of 4.08 MN per 500 LCA (p<0.01). CONCLUSION: The I131 therapy induces a significant increase of chromosomal damage of the lymphocytes from thyroid cancer patients receiving I131 radiation, that has an equivalent TBI of 13 cGy during the first three days of treatment.
: Radiation effects; Lymphocytes; Micronuclei; Thyroid cancer.