The center responsible for treatment is also responsible for follow-up of the patient. This should be in collaboration with the primary care doctor.
A risk assessment is performed at least six months after treatment is concluded and is based on:
- the physical exam
- results from the image testing
- post therapy scan
- ultrasound of the neck
- eventually CT/MR of the thorax, and in some patients PET
- stimulated Tg in TgAb nevative patients
Risk assessment after completing primary treatment is very important in choosing the long-term follow-up plan.
The low risk group is defined as patients:
- without metastasis at diagnosis
- with tumors less than pT3 at diagnosis
- without a low differentiated histology at the primary diagnosis
- who have had adequate surgery and radioablation
- without sign of disease at the follow-up examination 6-12 months after primary treatment (including stimulated Tg < 0,2 µg/l)
- who have not been previously irradiated to the throat
Patients who do not fit into the low risk group are considered high risk patients.
Patients with advanced disease at the time of the diagnosis have more frequent follow-up checks than patients in the low risk group, even if both groups are classified as low risk after treatment.
All patients who have had a thyroidectomy will either have suppression treatment or substitution treatment with thyroid hormones, and must have life-long follow-up with at least an annual monitoring of s-TSH, s-FT4 and s-calcium.
Low risk patients without thyroglobulin-antibodies (total thyroidectomy)
The follow-up plan for low risk patients without thyroglobulin-antibodies is available in an interactive flow chart, which provides overview of follow-up for different patient groups.
Click here to open the flow chart:
Patients having a hemithyroidectomy have a follow-up yearly with Tg testing. The Tg value must be monitored closely. The baseline value may be measurable (up to 10 µg/l, rarely higher). An elevation may be due to cancer or a change in normal remaining gland tissue, and will depend on the TSH level.
A clinical examination and ultrasound of the neck should be performed every 2-3 years.
Conditions requiring other types of follow-up testing
With an elevated Tg (stimulated or unstimulated), Tg and TgAb must be monitored in combination with FT4 and TSH. An ultrasound of the neck should also be performed. Radioactive iodine is given as a diagnostic scan, or possibly as a direct therapy dose. A thoracic CT is done and possibly a PET/CT directly.
Low risk patient with TgAb
These patients, as long as they are TgAb positive, must be examined with:
- measurement of Tg and TgAb
- rhTSH or endogenous stimulated whole body scintigraphy (WBS)
- CT thorax, possibly PET/CT
Uptake outside the thyroid bed on whole body scintigraphy after ablation dose
Patients with uptake outside the thyroid bed on the post ablation scan must have further testing. An ultrasound, CT, MRI, and possibly PET/CT are taken to ensure localization of metastases/cancer remains for surgery, or radioactive iodine therapy if surgery is not possible. PET/CT scan should be performed stimulated.
Tg positive - radioactive iodine-negative patients
Patients with an elevated Tg level in the blood but no iodine uptake on whole body scintigraphy have a high probability of cancer remains/metastases that are not concentrating iodine. These pose a diagnostic and therapeutic challenge.
An explanation of the lack of iodine uptake is that the disease has dedifferentiated and lost its ability of iodine accumulation. These patients therefore require further testing with ultrasound, CT, PET, and possibly MRI to localize the disease and to evaluate for treatment (surgery, possibly external radiation therapy). Metastatic foci that are smaller than the resolution of the camera may also be present. In these cases, Tg will rise 3-5 days after radioactive iodine therapy, and Tg will fall after each treatment with radioactive iodine.
Pregnancy after primary treatment
If the patient is planning on becoming pregnant, differentiated thyroid carcinoma is not a contraindication. However:
- it is not recommended to become pregnant before treatment is completed and the planned therapy doses are given
- one year should pass from the last radioactive iodine ablation/therapy dose
- thyroid hormones should be stable
It is very important for fetal development that thyroid hormones are optimal and stable through the entire pregnancy. The need for thyroxine increases during pregnancy, mostly in the first half (10-80% increase), but in those undergoing suppression treatment, it is normally not necessary to increase the dosage. Pregnant patients must be monitored closely through the entire term. Both overdosing and deficiency of thyroxine is harmful to the fetus.