Radioactive iodine therapy

Radioactive iodine therapy

Patients with thyroid cancer may receive treatment with radioactive iodine (I-131). The thyroid gland absorbs nearly all the iodine in the blood. When a large dose of radioactive iodine is taken into the body, it can destroy the thyroid gland and thyroid cancer cells with minimal effect on the rest of the body. The goal of this treatment is to target and kill any remaining thyroid cells or thyroid cancer cells anywhere in the body. The patient takes radioactive iodine as a capsule or liquid to treat slow growing differentiated thyroid cancers, also called papillary and follicular thyroid cancer. It is not used to treat medullary or anaplastic thyroid cancer as these cancer types do not take up iodine. During treatment, it is important that patients take specific precautions that are explained by their physician until the medication is out of the body.

Radioactive iodine therapy is most effective if a patient has high blood levels of thyroid stimulating hormone (TSH), which causes thyroid cells in the body, including thyroid cancer cells, to take up the iodine. After thyroid surgery, the patient may be given a drug called Thyrogen (thyrotropin) to raise TSH levels before treatment. TSH levels can also be raised by not taking thyroid hormone after surgery for a few weeks. The patient may be instructed to follow a low-iodine diet for a few weeks before treatment.

During radioactive iodine therapy for thyroid cancer, the patient will take radioactive iodine as a pill or liquid. Any remaining thyroid cells ingest the iodine, and the cells are destroyed. Thyroid scans may follow this type of radiation to show whether there is any remaining cancer.

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