Thyroid Cancer Recurrence: What to Ask

This page is for people whose thyroid cancer may come back. It covers the blood tests and scans used. It explains what happens when iodine stops working. It ends with questions to ask.

For papillary and follicular thyroid cancer, a blood protein called thyroglobulin does most of the work in follow-up.

NCI is direct about it. A raised thyroglobulin level after surgery correlates strongly with cancer having returned.

There is a catch in how the test behaves. NCI says thyroglobulin is most sensitive when your thyroid hormone is low and TSH (thyroid-stimulating hormone) is high. Preparing for the test therefore involves raising TSH. There are two ways to do this. One is to pause or change the thyroid hormone tablet for a set time. The other is a shot of recombinant (lab-made) TSH, so the tablet can continue. Which route suits you is an endocrinology decision.

Never stop, reduce or change your thyroid hormone yourself, and never skip doses in preparation for a test or a scan unless endocrinology has told you to, in writing, with dates. Ask which conditions your sample was taken under, and whether it can be compared with your earlier results.

This is worth understanding, because it explains the follow-up. NCI says the goal of radioactive iodine after surgery is to destroy leftover normal thyroid tissue.

That is not only about cancer. Removing the remnant makes the thyroglobulin test more meaningful and lets a whole-body scan pick up disease that is still there.

NCI adds that a large remnant makes a low thyroglobulin impossible to reach, which can mean more doses.

NCI describes careful follow-up for differentiated thyroid cancer. It uses physical examinations, quantitative thyroglobulin blood tests, and imaging chosen according to individual risk.

Risk-based means your schedule may differ from someone else's, and it should. Ask what risk group you are in and why.

Not every recurrence takes up iodine. NCI lists what decides the next step:

• The cell type
• Whether the tumor takes up iodine
• What treatment you have already had
• Where the recurrence sits
• Your own preferences
• Whether the tumor carries an activating RET or NTRK gene fusion

For recurrent papillary and follicular cancer, NCI lists:

• Surgery with or without iodine
• Targeted therapy, including tyrosine kinase inhibitors, RET inhibitors and NTRK inhibitors
• External beam radiation
• Chemotherapy

NCI reports that in differentiated thyroid cancer, people whose recurrence is picked up only by an iodine scan have a better outlook than those whose recurrence is clinically obvious. That is a comparison between two groups, not a forecast: where the disease is, how much there is, whether it still takes up iodine and what treatment is open all move the answer. Medullary and anaplastic disease are followed and judged on their own terms.

That is an argument for taking the scan seriously, not for dreading it.

Medullary cancer usually makes calcitonin. NCI says a raised calcitonin level in the blood is what makes doctors suspect it. The level is also used to follow treatment.

If yours is medullary, ask whether RET testing was done. NCI's genetics summary recommends it for everyone with this type, even when no one else in the family has had it. If a RET change is found, NCI says testing at-risk relatives can help.

• What is my thyroglobulin now, and what was it before?
• Was the sample taken on or off my hormone tablet?
• Which risk group am I in, and what schedule does that set?
• Did my neck ultrasound find anything that needs a biopsy?
• Does my tumor still take up iodine?
• Has the tumor been tested for RET or NTRK changes?
• If iodine will not work, which treatment comes next?

Most thyroid recurrences are found by a blood test or a scan, not by a symptom. A few things should not wait for the next appointment.

• Call 911 or go to an emergency department if breathing becomes difficult or noisy, or the airway feels like it is closing. A recurrence in the neck can press on the windpipe. Go too for a seizure, fainting, or an irregular heartbeat, or for muscle spasms that make it hard to breathe. MedlinePlus lists seizures, an abnormal heart rhythm and throat spasms that affect breathing as effects of low calcium. It says seizures or breathing problems are an emergency. Fainting is on our list as a cautious step. Do not drive yourself.
• Call your care team right away if you get tingling in the lips, fingers or toes, or muscle cramps or spasms, especially after neck surgery. MedlinePlus lists these as the most common signs of low calcium. It says the most common cause of low calcium is injury to the parathyroid glands during thyroid or neck surgery. Low calcium is treated with calcium and vitamin D, so call and do not wait.
• Call your care team the same day if you notice a new neck lump, a new or worsening hoarse voice, trouble swallowing, or pain on swallowing. NCI lists all of these as signs of thyroid cancer. If you are on chemotherapy, call right away, day or night, instead of waiting for the same day.

If a term above is new, Cancer Staging and Biomarker Testing cover the ones that come up most in thyroid follow-up. For what to do with the answers, see Clinical Trial vs Standard Treatment, Palliative Care, and Questions to Ask Your Doctor.

These questions were drawn from current patient guidance for thyroid cancer:

• NCI PDQ - Thyroid Cancer Treatment (Patient Version).
• NCI PDQ - Thyroid Cancer Treatment (Health Professional Version).
• NCI PDQ - Multiple Endocrine Neoplasia Type 2 (Health Professional Version).
• MedlinePlus - Hypoparathyroidism.