After patients have completed treatment for well-differentiated thyroid cancer, they will need to have close follow-up with their doctor. Initially, an endocrinologist will help screen for possible endocrine, or hormonal, complications resulting from surgery.
Finding the right dosage of thyroid hormone replacement after surgery is essential. Thyroid hormone replacement is important for two main reasons. Firstly, since some or all of the thyroid gland has been removed, this therapy helps restore the thyroid hormone levels in the body. Secondly, thyroid hormone therapy keeps TSH levels low, which helps to reduce the risk of disease recurrence. Doctors will periodically order blood tests and imaging studies in order to monitor the disease.
Thyroglobulin & Thyroglobulin Antibodies
Thyroglobulin (Tg) is a protein found in thyroid tissue, it is an essential ingredient in thyroid hormone production. Normally, Tg drops significantly in patients after total thyroidectomy and RAI treatment. Therefore, postoperative elevation in Tg levels is considered an indirect sign of disease recurrence or progression, and requires further investigation.
Anti-Tg antibodies (TgAb) are also helpful in the evaluation of disease recurrence. When anti-Tg antibodies are high, the results from Tg assays are not considered trustworthy, since the appearance of anti-Tg antibodies in the blood can cross react with Tg and give false results.
After initial surgery Tg and anti-Tg antibodies should be monitored periodically and, if at all possible, by the same laboratory, to avoid variables that could make interpretation difficult. Initially serum Tg should be measured every 6–12 months, or more frequently in high-risk patients.
It is important to note that for many patients who have undergone a hemi-thyroidectomy, their thyroid function will remain normal, despite the removal of half of the thyroid gland. For these patients, thyroglobulin should not be used as a marker of disease status, as levels found might not reflect the course of the disease. These patients should be monitored with imaging studies, as explained below.
Imaging studies
Doctors will perform imaging in the first 6 months after treatment. This is usually an ultrasound, and the first ultrasound will serve as a “baseline” study for the purpose of comparing future studies. During every follow-up visit after “baseline” evaluation, patients will be sent for imaging studies to help monitor for the presence of disease.
Occasionally, when ultrasound exams are normal, but blood tests (Tg and anti-Tg antibodies) are elevated, other imaging studies can be used such as a CT, MRI, or PET/CT scan. If something suspicious comes up, a biopsy might be helpful to rule out disease recurrence.
RAI uptake scans, or functional tests may also be used, because uptake of radioactive iodine can help to localize any recurrent disease in the neck or distant metastasis elsewhere in the body.
Follow-up Schedule
Patients should visit their specialist on a regular basis (or earlier if they have any concerning symptoms). This allows doctors to examine for any sign that the cancer has returned. The best timeline for follow-up will be determined by the doctor.
Standard Follow-up Schedule
- For the first year, go every 1–3 months.
- For the second year, go every 2–6 months.
- For the third to fifth year, go every 4–8 months.
- After five years, start going once annually.
According to the results of the blood tests and imaging studies, patient’s response to therapy will be re-assessed at every follow up visit in order to plan subsequent visits or any necessary future treatments.
