“How is nuclear medicine used to treat thyroid cancer?”
I have been diagnosed with thyroid cancer and have also been told that nuclear medicine helps best in treating this. Can you please explain how would it work?
2 Answers
Radioactive iodine is the ideal therapeutic agent for well differentiated thyroid cancer. The iodine (I-131) is administered as a capsule. The iodine goes to the thyroid (normal and cancerous) and kills the cells. The dose of I-131 is dependent on the specifics of the tumor and whether or not there is metastatic disease elsewhere. After thyroidectomy, thyroid hormone is suspended for a while or the patient may receive two intramuscular injections of a thyroid stimulating hormone. A small dose of I-131 is administered to see how much and where thyroid tissue is left. After receiving radioactive iodine, there are some quarantine issues to prevent exposure to others.
Thyroid cells use iodine to make thyroid hormone, which is responsible for a myriad of regulatory functions in the body. As such, when a small amount of the radioactive isotope of iodine is given orally, I-131, it is taken up by both normal and cancer thyroid cells.
Typically, after a diagnosis of thyroid cancer, surgery is performed to removed the entire gland. Even in the hands of the best surgeon, there is often residual thyroid tissue remaining in the neck as surgeons are especially careful when operating in the neck due to multiple vascular and nerve structures in such a compact space. So, in order to "clean up" any
minute deposits of thyroid tissue, that can either be normal or cancerous, radioactive I-131 is given to kill or "ablate" any thyroid cells. Ablation is also helpful because it makes it easier to check if there is recurrence in the future by checking a protein in your blood called thyroglobulin, that is made by thyroid tissue. Since your gland will be removed and
ablation administered to destroy any remaining normal or cancer thyroid cells, a thyroglobulin level drawn from your blood several months later should be undetectable. If it is detectable, then there is concern that there is recurrent disease. A caveat to this is some people develop antibodies to thyroglobulin which makes a blood levels of the protein
unreliable. As such, follow-up is based solely on imaging (neck ultrasound which is done even if a person doesn’t make antibodies to thyroglobulin, a I-123 iodine scan, which you may get before ablation as well to assess how much residual tissue is in your neck, and sometimes a PET/CT if warranted). The size and type of thyroid cancer you have will determine the dose you receive.
People hear "radioactive" and are immediately afraid something weird will happen to them or they it’s dangerous. This is one of the safest, most effective treatments for thyroid cancer; so much so that it has been essentially unchanged and performed for over 70 years.
I hope this answers your question!
Typically, after a diagnosis of thyroid cancer, surgery is performed to removed the entire gland. Even in the hands of the best surgeon, there is often residual thyroid tissue remaining in the neck as surgeons are especially careful when operating in the neck due to multiple vascular and nerve structures in such a compact space. So, in order to "clean up" any
minute deposits of thyroid tissue, that can either be normal or cancerous, radioactive I-131 is given to kill or "ablate" any thyroid cells. Ablation is also helpful because it makes it easier to check if there is recurrence in the future by checking a protein in your blood called thyroglobulin, that is made by thyroid tissue. Since your gland will be removed and
ablation administered to destroy any remaining normal or cancer thyroid cells, a thyroglobulin level drawn from your blood several months later should be undetectable. If it is detectable, then there is concern that there is recurrent disease. A caveat to this is some people develop antibodies to thyroglobulin which makes a blood levels of the protein
unreliable. As such, follow-up is based solely on imaging (neck ultrasound which is done even if a person doesn’t make antibodies to thyroglobulin, a I-123 iodine scan, which you may get before ablation as well to assess how much residual tissue is in your neck, and sometimes a PET/CT if warranted). The size and type of thyroid cancer you have will determine the dose you receive.
People hear "radioactive" and are immediately afraid something weird will happen to them or they it’s dangerous. This is one of the safest, most effective treatments for thyroid cancer; so much so that it has been essentially unchanged and performed for over 70 years.
I hope this answers your question!
