Anaplastic Thyroid Carcinoma Following Radioactive Iodine Therapy for Graves' Disease

Abstract

Radioactive iodine (RAI) therapy has been used as a treatment option for Graves' disease, and it has been widely accepted to be safe. On the other hand, some evidence suggests that RAI therapy is possibly associated with a small increased risk of thyroid cancer. Herein, we report a rare case of anaplastic thyroid carcinoma (ATC) associated with Graves' disease, following RAI treatment. A 42-year-old woman had been diagnosed with Graves' disease and although she was treated with an antithyroid drug, she remained in a hyperthyroid state, which led to two RAI treatments. More than 10 years later, the patient revisited our clinic due to hoarseness, dysphagia, and dyspnea, which had lasted for 2 months. Neck computed tomography suggested thyroid carcinoma and a lymph node biopsy showed metastatic papillary carcinoma. The patient underwent total thyroidectomy and was finally diagnosed as having an ATC. It is not clear if the occurrence of ATC reported here was influenced by the RAI therapy or alternatively, it may only represent the delayed recognition of a rare change in the natural history of Graves' disease. Nevertheless, this report is worthwhile since it presents a very rare case of ATC that occurred eleven years after the RAI therapy for Graves' disease.

Rak tarczycy po terapii jodem radioaktywnym z powodu nadczynności tarczycy — opis serii przypadków i przegląd piśmiennictwa

“…Radioactive iodine treatment plays a significant role in induction of cellular atypia with progressive metaplastic changes in patients with Graves' disease. This phenomenon is actually prominent in those who remain hyperthyroid after treatment with radioactive iodine [26].…”

“…This cancer was elicited 12-20 years after RAI 131 [26][27][28]. The Cooperative Thyrotoxicosis Therapy Follow-up Study concluded that thyroid cancer after radioactive iodine ablation developed in those people receiving lower rather than higher doses of RAI 131 therapy [29].…”

Evaluation of ultrasonographical and cytological features of thyroid nodules in patients treated with radioactive iodine for hyperthyroidism

“…The I 131 isotope emits both particles and rays, but the effect on the thyrocytes is primarily through particle radiation. 44 It was speculated that radiation therapy in the presence of a differentiated tumor might play role in the transformation to an undifferentiated tumor. This results with decreased thyroid function and/or a reduction of the thyroid volume.…”

“…43 In the report by Kim et al, anaplastic carcinoma was diagnosed in middle-aged women who had received RAI therapy twice for recurrent hyperthyroidism more than 10 years ago. 44 It was speculated that radiation therapy in the presence of a differentiated tumor might play role in the transformation to an undifferentiated tumor. p53 positivity was observed in the lymph node of a papillary thyroid cancer patient after two doses of RAI treatment.…”

Brief Review of Articles in 'Endocrinology and Metabolism' in 2013

“…They found TAMs in primary PTC tumors with lymph node metastasis, and higher TAM densities were related to larger tumors, suggesting a tumorigenic role of TAMs in human PTCs [ 6 ]. Interesting case reports about various thyroid diseases were presented in 2013 issues of ' Endocrinology and Metabolism ' [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”