A cytogenetic follow-up study of thyroid cancer patients treated with 131I.

To determine the genotoxic risk associated with therapeutic exposure to 131I, we studied the presence of micronuclei (MN) in binucleated peripheral blood lymphocytes of a group of 22 women, patients of thyroid cancer, who received 131I sodium iodide orally as an adjuvant after total thyroidectomy. The cytogenetic study was conducted following annual check-up, the patients having received the therapeutic dose between 1 and 5 years before the study. The results show that there are no significant differences in MN frequency between the patients and the control group, the latter composed of 19 unexposed women. These findings could indicate that any possible genetic damage induced by therapeutic exposure to 131I is eliminated after a period of 1 year.