Monitoring for Thyroid Cancer Recurrence
Mary Shomon | Oct 16, 2017
After you have been treated for thyroid cancer, thyroid cancer can recur. As a result, your doctor will recommend lifelong monitoring for early detection of any potential recurrence of your thyroid cancer. The goals of monitoring include:
- Ensuring that you are on the correct dose of thyroid hormone replacement. This requires periodic blood tests and potential adjustments to your dosage of thyroid medication.
- Determining if you have any persistent thyroid cancer or a recurrence.
Frequency of monitoring and follow-up
You will need more frequent follow-up and monitoring after surgery and after you start thyroid hormone medication. It’s common to see your doctor every three to six months in the first two years after diagnosis. If you are disease-free with no signs of recurrence, your doctor may recommend less frequent monitoring. If you had higher-stage cancer, a more aggressive thyroid cancer, or show evidence of persistent disease, your doctor is likely to recommend more frequent monitoring.
During visits to your physician, it is likely that he or she will feel your thyroid area, looking for any enlargement, lumps, or changes. This will typically be done every three or six months during the first two years after your thyroid cancer diagnosis, and annually thereafter, at a minimum.
Blood testing for thyroid hormone replacement
After starting thyroid hormone replacement, you are likely to have frequent blood tests — often every three months — until your thyroid stimulating hormone (TSH) levels have stabilized. Thereafter, thyroid testing is typically done every six or 12 months to continue to ensure that you are on the right dosage of thyroid hormone replacement medication.
Thyroglobulin (Tg) testing
If you had papillary or follicular thyroid cancer, your doctor will periodically perform a blood test to measure your thyroglobulin (Tg) levels. Thyroglobulin is a protein made by thyroid tissue and should be low or undetectable after thyroid surgery and radioactive iodine treatment. (Note that it can take months or years after surgery and RAI, however, for your Tg number to become low or undetectable.) If your Tg levels rise over time, this can be evidence of a thyroid cancer recurrence.
Anti-thyroglobulin antibodies (TgAb)
The presence of anti-thyroglobulin antibodies can make the thyroglobulin test less reliable. If you had papillary or follicular thyroid cancer, you will usually be tested periodically for TgAb. If these antibodies are evident, your doctors will not rely on thyroglobulin levels as a cancer marker.
Medullary thyroid cancer monitoring
If you had medullary thyroid cancer, your doctor will run blood tests to measure your levels of calcitonin and carcinoembryonic antigen (CEA). If these levels rise, this suggests a possible recurrence of your thyroid cancer. Your doctor would then likely schedule an ultrasound, computerize tomography (CT), and/or magnetic resonance imaging (MRI) test to look for any sites of thyroid cancer recurrence.
Ultrasound testing is increasingly included as part of monitoring for recurrence because it can help detect any growths or changes in your thyroid area. The frequency of ultrasound testing will depend on whether you are disease-free or still have evidence of thyroid cancer, and on the type and staging of your thyroid cancer.
Monitoring for thyroid cancer recurrence may include imaging tests, such as:
- CT scans (without an iodine contrast dye) of your head and neck area. Iodine contrast is not used because if a cancer recurrence is detected, it can delay subsequent treatment.
- MRI of your head and neck area, using gadolinium contrast.
- Positron emission tomography (PET)/CT scan, especially if your thyroglobulin levels are elevated, to pinpoint any locations of cancer recurrence or spread.
Radioactive iodine scan
If you had papillary or follicular thyroid cancer, your doctor may recommend a radioactive iodine nuclear scan. An accurate scan requires you to stop taking your thyroid hormone medication for several weeks. (Most patients then receive a thyrotropin alfa injection, known as Thyrogen, to relieve hypothyroidism symptoms.) You need to follow a low-iodine diet for several weeks prior to the scan. After the scan, your doctor will instruct you regarding restarting your thyroid medication.
Monitoring for a secondary cancer
Survivors of thyroid cancer are at an increased risk of the following cancers:
- breast (in women)
- prostate (in men)
- Adrenals (higher risk after medullary cancer)
If you had radioactive iodine, you’re at increased risk of lymphocytic leukemia, and cancer of the stomach and salivary gland.
Testing for secondary cancers is only done if you have symptoms. But it’s important to stay informed by reviewing the American Cancer Society guidelines for the early detection of cancer.