Unfortunately, cancerous cells can return many years after surgery and radioactive iodine treatment has been completed.
It is estimated that 5-20% of people with a history of thyroid cancer will experience a return of cancerous cells in their neck. An estimated 10-15% of people will experience a return of cancerous cells in other parts of their body, such as their bones.
Due to the risk of cancer cells returning, you will be asked to attend regular check-ups so any cancerous cells that do return can be quickly treated.
Thyroglobulin testing
Thyroglobulin testing is the main method used to check for the return of cancerous cells.
Thyroglobulin is a protein released by a healthy thyroid gland, but it can also be released by cancerous cells.
If you have had your thyroid gland removed, there should be no thyroglobulin present in your blood, unless cancerous cells have returned.
Therefore, regularly testing your blood for thyroglobulin can be an effective way of checking whether or not any cancerous cells have returned.
For the first few years after surgery, you will probably need to have thyroglobulin testing every six months. After this time, testing will be required once a year.
Other tests
Other tests that may be used to check for the reoccurrence of cancerous cells include:
- an ultrasound scan of the neck
- a radioactive iodine scan
These tests are described below.
Ultrasound scan
An ultrasound scanner uses high frequency sound waves to create an image of part of the inside of the body. Ultrasound scans can be a useful way of detecting any changes or abnormalities inside your neck that could indicate the recurrence of cancer.
Ultrasound scans are increasingly being used in combination with thyroglobulin testing because research suggests it is an effective method of detecting recurring thyroid cancer.
Radioactive iodine scan
After having surgery to remove part or all of your thyroid gland, you may be asked to attend a radioactive iodine scanning test.
The test involves swallowing a small amount of radioactive iodine before your body is scanned using a special camera. The radioactive iodine will highlight any cancerous thyroid cells remaining in your body.
The preparation for an iodine scan is similar to having radioactive iodine treatment. You will need to go on a low iodine diet and stop taking your thyroid hormone medication. Alternatively, recombinant human thyroid stimulating hormone (rhTSH) can be used without having to interrupt your thyroid hormone medication.
As the dose of radioactive iodine used for the scan is very small, no precautions, such as keeping your distance from others, are required. However, if you think you may be pregnant, or if you are breastfeeding, you must let the doctors know before your test.
A radioactive iodine scan will usually be carried out six to eight months after surgery. If the test results are negative, further testing is not usually required.