How is radioactive iodine therapy used in treatment of thyroid cancer?
Patients who have thyroid cancer are usually treated surgically initially, by removal normally of the entire thyroid gland. That is called a total thyroidectomy. Then after that, the patient is usually treated with what we call appellation dose, radio iodine treatment and this is done sometime shortly after the surgery is finished, maybe a week or two after the surgery is done. The reason for that is to basically kill all the residual thyroid tissue that is left behind by the surgeon in the niche. At the same time it can show us if there are other sites, distance sites or local sites, in the body that the thyroid cancer has already metastasized. Then, after the treatment, the patient comes back to the nuclear medicine clinic in about 6 months, or sometimes a year depending upon their referring physician and their clinical condition, to see if there is evidence for recurrence of thyroid cancer that can be signalled by following or marking their blood which is called thyrogloblaring. Thyrogloblaring is produced by the thyroid tissue, so if in a patient that does not have a thyroid, after its resection shows that the thyroglobarling in their blood is going up, we know that there is thyroid tissue somewhere and therefore that prompts the patients for another radio iodine diagnostic scan. This is a low dose scan to see where the thyrogloblaring is coming from, and depending on what is seen on that survey, if there is for example evidence of an extetic disease, the patient is scheduled for a much larger dose of radio iodine treatment, and the amount of dose depends on how extensive the disease is.
