Anaplastic Changes Associated with p53 Gene Mutation in Differentiated Thyroid Carcinoma After Insufficient Radioactive Iodine ( 131 I) Therapy

Thirty-two patients with differentiated thyroid carcinomas with distant metastasis were examined using a radioactive iodine (¹³¹I) tracer dose prior to ¹³¹I therapy and followed up for 10 years or until death (whichever occurred first). Nineteen patients who received ¹³¹I therapy had an accumulation of ¹³¹I in the metastases (group I) and 15 of those patients were alive more than 10 years after the first 131I treatment. In contrast, all 13 patients in whom the metastases did not show accumulation of 131I died within 10 years. Of the latter group, eight patients had received ¹³¹I therapy (group II), four of whom died with anaplastic changes within 5 years of treatment. p53 gene mutation was identified by immunohistochemistry in primary thyroid carcinoma tissue from patients with anaplastic changes that were evident during total thyroidectomy. Five patients did not receive ¹³¹I therapy (group III), of whom one, who also had a p53 gene mutation in the original tumor, died with anaplastic change 10 years after thyroidectomy. Seven patients in group I had p53 gene mutations in their thyroid carcinoma tissues, but none showed anaplastic changes. Our results suggest that ¹³¹I therapy may be useful for patients with distant metastases, with or without p53 gene mutations, which show accumulation of ¹³¹I from tracer and therapeutic doses. In contrast, ¹³¹I therapy is apparently not effective in patients who do not show sufficient accumulation of ¹³¹I, but rather, may cause early anaplastic changes with a p53 gene mutation.