J Korean Thyroid Assoc.  2013 May;6(1):49-55. 10.11106/jkta.2013.6.1.49.

RAI Treatment of Distant Metastasis of Thyroid Cancer

• Kang KW

• KMID: 1428453
• DOI: http://doi.org/10.11106/jkta.2013.6.1.49

Abstract

For the distant metastasis of differentiated thyroid cancers, such as papillary thyroid carcinoma, follicular thyroid carcinoma, and Hurthle cell carcinoma, radioiodine therapy is one of the standard treatment methods after total thyroidectomy. Radioiodine is accumulated in thyroid cells and thyroid cancer cells through sodium iodide symporter which is located in the membrane of cells. This molecular target specific therapy renders a better prognosis and less adverse effects. Radioiodine 131I emits gamma ray for imaging and beta ray for treatment at the same time, we can monitor patients' specific distribution of radioiodine, which let us know unexpected metastasis lesions or differentiated status of thyroid cancer cells. In this article, I reviewed practical points of view about radioiodine therapy for distant metastasis of thyroid cancers such as methods for administration of radioiodine, patients' preparation before radioiodine treatment, follow up of patients, adverse effects, and radiation safety issues.

Keyword

Thyroid cancer; Radioiodine; Metastasis

MeSH Terms

Adenocarcinoma, Follicular
Beta Particles
Carcinoma
Enzyme Multiplied Immunoassay Technique
Follow-Up Studies
Gamma Rays
Humans
Ion Transport
Linear Energy Transfer
Membranes
Neoplasm Metastasis
Organothiophosphorus Compounds
Prognosis
Sodium Iodide
Symporters
Thyroid Gland
Thyroid Neoplasms
Thyroidectomy
Carcinoma
Organothiophosphorus Compounds
Sodium Iodide
Symporters
Thyroid Neoplasms

Figure

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  Fig. 1. Whole body scans after serial radioiodine therapies in a patient with papillary thyroid cancer. Initial whole body scan after 1.1 GBq (30 mCi) of radioiodine therapy showed remnant thyroid and mediastinal lymph node metastasis. New lesions were revealed in right supraclavicular lymph nodes on whole body scan after 7.4 GBq (200 mCi) high dose radioiodine therapy about 4 months later. Multiple metastatic lesions were not visualized in initial scan due to higher affinity of radioiodine in normal thyroid tissue than thyroid cancer. After repeated 7.4 GBq of radioiodine therapies, metastatic lesions decreased and finally disappeared.

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  Fig. 2. 131I scan versus 123I scan. 123I scan (B) is clearer than 131I scan (A) and reveals small lesions.

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  Fig. 3. Diagnostic radioiodine scan (A) versus scan after radioiodine therapy (B). Diffuse lung metastasis was found out on a scan after radioiodine therapy which was not visualized on a small dose of diagnostic scan.

Reference

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