Effects of different doses of iodine-131 on tumor suppressor gene expression, thyroid hormone and chromosomal aberrations in patients after thyroid cancer surgery

  Objective  To explore the effects of different doses of iodine-131 (¹³¹I) on tumor suppressor gene expression, thyroid hormone and chromosomal aberrations in patients after thyroid cancer (TC) surgeries.

  Methods  Clinical materials of 120 patients with the first time ¹³¹I treatment after TC operation were analyzed retrospectively, and they were divided into low dose group (n=48), medium dose group (n=40) and high dose group (n=32) according to the dose of ¹³¹I treatment. The differences of tumor suppressor gene expression, thyroid hormone and chromosomal aberrations after ¹³¹I treatment were compared among the three groups.

  Results  Compared with the low dose group, the mRNA and protein expressions of CCNG2 and PTEN genes in the medium dose group and high dose group were significantly higher (P < 0.05). After treatment, the levels of thyroid stimulating hormone (TSH), free triiodothyronine (FT₃) and free thyroxine (FT₄) in the three groups were significantly lower than those before treatment, and the high-dose group was the lowest and the low-dose group was the highest (P < 0.05). At 7 days after treatment, the total chromosome aberration rate as well as bicentromeric body and centromeric ring rate of the three groups were significantly higher than those before treatment (P < 0.05).

  Conclusion  High dose ¹³¹I treatment for patients with TC after surgery can promote the expression of tumor suppressor genes and reduce the level of thyroid hormone without increasing the rate of chromosomal aberrations, which can be used as the ideal dose of ¹³¹I treatment under the patient's tolerance.