Thyroid Cancer, from the CureRays guide library.

Thyroid cancer forms in the butterfly-shaped gland in the neck; most types are highly curable, often with surgery and radioactive iodine rather than external radiation.

What it is.

The thyroid is a small, butterfly-shaped gland at the base of the neck that makes hormones controlling metabolism. Thyroid cancer usually appears as a painless lump or nodule and is often found incidentally on an exam or scan. Most thyroid cancers grow slowly and are among the most curable of all cancers — many are treated successfully with surgery, sometimes followed by radioactive iodine, a special internal radiation that the thyroid naturally absorbs. A small number of aggressive types need more intensive treatment, but for the great majority the long-term outlook is excellent.

How radiation treats it.

Two kinds of radiation help in thyroid cancer. Radioactive iodine is internal radiation: thyroid and most differentiated thyroid-cancer cells absorb iodine, so swallowed radioactive iodine collects inside them and destroys them from within while sparing other tissues. External-beam radiation uses focused high-energy x-rays from a machine to damage cancer-cell DNA in tumors that don't take up iodine or have grown into neck structures, with advanced planning to protect the voice box, swallowing muscles, and spinal cord. Both approaches are painless; radioactive iodine involves brief precautions to limit others' exposure, and external radiation may cause temporary neck soreness or dry mouth that settles afterward.

The ways we can treat it.

Radioactive iodine (internal radiation). Because thyroid cells naturally take up iodine, swallowed radioactive iodine concentrates in any remaining thyroid or cancer cells and destroys them while largely sparing the rest of the body.

External-beam radiation (IMRT). Precisely shaped external radiation treats aggressive cancers, those that don't absorb iodine, or tumors growing into neck structures — protecting the voice box, swallowing muscles, and spinal cord.

Palliative / stereotactic radiation. Focused treatment controls a painful or threatening spot of spread (such as in bone), relieving symptoms and stabilizing disease.

Questions we hear often.

Is thyroid cancer really that curable? For the common papillary and follicular types, yes — long-term survival is very high, especially when found early. Most people are cured with surgery, sometimes with radioactive iodine, and go on to live normal lives.

Will I need to take a pill for life? If your whole thyroid is removed, you'll take a daily thyroid-hormone pill to replace what the gland made. It's well tolerated and keeps your metabolism normal; doses are fine-tuned with simple blood tests.

What is radioactive iodine like? It's usually a single capsule or drink. Thyroid cells absorb it and are destroyed from within. You'll follow brief precautions for a few days to limit radiation exposure to others, then return to normal activity.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.