Monitoring and Follow-up
People who have had thyroid cancer must undergo regular monitoring to make sure the cancer does not return. Routine blood tests are also done to make sure you're on the proper amount of thyroid hormone replacement. As we said, that usually means a low TSH level. In people with medullary cancer, blood tests can reveal higher-than-normal levels of calcitonin.
Any abnormalities in the blood should prompt your doctor to do imaging tests to look for cancer. If the cancer does recur, you may need more surgery, RAI, radiation, or chemotherapy, depending on the location of the cancer and the extent of its spread.
To figure out whether your cancer has come back, your doctor may perform a thyroglobulin test and/or a whole body scan. Both tests require that you have elevated levels of TSH to stimulate any lingering thyroid cells — cancerous or not — to produce thyroglobulin or take up the RAI.
Normal healthy thyroid glands produce a protein called thyroglobulin (Tg). Anyone who has had a total thyroidectomy should have very little Tg in her blood. If it does show up in normal or high amounts, it can mean a return of cancerous thyroid cells, which will require further testing.
A single abnormal test, however, is not a definite sign of cancer. Whether the Tg levels rise steadily over time is more important, so your doctor may do more than one test. Also, some thyroid cancer patients may produce antibodies to thyroglobulin (TgAb), which can interfere with the test results. For that reason, your doctor may test for TgAb too. Most people who have had thyroid cancer will be tested for Tg annually.
Whole Body Scans
After your thyroid has been removed, your doctor may perform a whole body scan to look for recurrent thyroid cancer. To prepare for this procedure, you will need sufficiently elevated TSH levels and low levels of ordinary iodine in your body.
When you do discontinue your thyroid hormone therapy, make sure to take measures to ensure your safety. Do not operate a car or any heavy machinery, and if possible, take time off from work. Do not use this time to do anything that requires a lot of mental effort or energy.
Until recently, raising your TSH levels — either for testing or for RAI treatment — required that you stop taking your hormone treatments and go into a state of hypothyroidism, sometimes for several weeks. For many people, this was rather uncomfortable. Now, there are two ways to raise your TSH levels that are less bothersome. Since 1998, most doctors have been using a drug called Thyrogen to raise TSH levels without discontinuing hormone therapy. Thyrogen is a synthetic version of TSH that has the same effect on lingering thyroid cells — it encourages them to take up the RAI, which makes them visible on the scan. However, Thyrogen is used only for diagnostic testing such as whole body scans and not for RAI treatment for cancer.
Another way to lessen the symptoms of hypothyroidism involves taking Cytomel (T3) six weeks prior to receiving the RAI. Two to three weeks before the RAI, you will discontinue the Cytomel.
After you are suitably prepared, and your TSH levels reach the required levels, you will undergo the whole body scan. For the scan itself, you will take a pill or injection that contains a small dose of RAI. You will then be scanned for cells that have taken up the RAI. The doctor will also test your Tg level at that time.
Whole body scans are used for detecting the recurrence of thyroid cancer or metastasis and use a much lower dose of RAI. You do not need to take measures to isolate yourself or shield others from radioactivity after the scan as you do when you get a high-dose RAI treatment.
Taking Care of Yourself
A great deal of follow-up cancer care rests with you, the patient. Follow your doctor's instructions closely on taking your medications and staying on a schedule of regular blood tests and checkups. Be vigilant about any changes in your body, and report them promptly to your doctor. If you're having a difficult time coping with the rigors of cancer treatment or surviving cancer, consider seeking out a mental health professional for counseling. Your state of mind will influence how well you fare after diagnosis and treatment for thyroid cancer, too.
We want to emphasize that it's very rare to die of thyroid cancer. Most people go on to live normal lives. The key is staying on top of your care.