Panorama Centre For Surgical Oncology
Managing a nodule in your thyroid
Thyroid nodules are a common finding in the general population. They are frequently found during physical examination or investigations for other symptoms. Thyroid nodules are much more common in women than in men. Nodules tend to grow during pregnancy. Although the risk of cancer is small, these lesions require further work-up.
The initial investigation needed is a blood test measuring thyroid hormone levels to exclude conditions that may cause overactivity of the thyroid. These require a different approach. When the thyroid is not overactive, an ultrasound is required. This will determine whether fine-needle aspiration is required.
These basic investigations allow us to stratify the risk of the nodule being cancerous and as such needing surgery.
The overactive thyroid
If the thyroid function is found to be overactive, a nuclear medicine scan using a special radio-active form of Technetium, will be done to further evaluate the thyroid and any possible nodules. This will reveal conditions such as Grave’s disease, Toxic nodule or Thyroiditis, each requiring a specific treatment.
Ultrasound of the thyroid
Ultrasonography is the imaging modality of choice. Several guidelines recommended biopsy of lesions over 1cm, but this has led to over investigation of thyroid nodules, especially those found incidentally during ultrasound of the neck for other reasons. In our unit, the TI-RADS system is used for risk stratification and to guide performing FNA biopsies. Only those with a TI-RADS score of 3 or more will be considered for FNA.
If more than one nodule is present, up to three might be biopsied with little benefit in sampling more than three.
Nodules of any size should be biopsied if ultrasonography suggests extracapsular invasion by the lesion or shows pathological cervical lymph nodes.
Nodules should also be biopsied if the patient has a history of head and neck irradiation, thyroid cancer, or MEN type 2 in a first-degree relative. Hyperfunctioning nodules should not be biopsied.
| Level of suspicion | TI-RADS score | Risk of cancer | Size for doing FNA |
|---|---|---|---|
|
Very Low |
1 |
<3% |
Observe only |
|
Low |
2 |
5-10% |
Follow-up |
|
Intermediate |
3 |
10-20% |
≥2.5cm |
|
Moderate |
4 |
20-40% |
≥1.5cm |
|
High |
5 |
>70% |
≥1cm |
Cytology
The aspiration of cells from the thyroid is called fine needle aspiration cytology (FNA). This is done by inserting a thin syringe needle into the thyroid nodule and aspirating some cells into the tip of the needle. Larger nodules may be biopsied without ultrasound guidance, but the use of ultrasonography generally improves the diagnostic accuracy of FNA allowing the targeting of specific areas.
Any nodule determined by FNA to be non-diagnostic or indeterminate should be reassessed with ultrasound guidance, if it was not used for the initial biopsy.
Most pathologists classify FNA specimens in one of 6 categories. To standardize reporting, the Bethesda classification is used as listed below. The malignant and benign categories are the most accurate, with false-negative rates of 1% to 10% and false-positive rates of about 2%.
| Pathological Description | Bethesda Category | Risk of cancer | Management Option |
|---|---|---|---|
|
Insufficient / Non-diagnostic |
1 |
Unpredictive / Generally <4% |
Repeat FNA. If still non-representative, surgery is indicated |
|
Benign / Non-malignant |
2 |
0-3% |
Follow-up only. Surgery only if symptomatic. |
|
Follicular lesion (Atypia of) of indeterminate significance |
3 |
5-15% |
|
|
(Suspicious for ) Follicular Neoplasm |
4 |
15-30% |
|
|
Suspicious for Malignancy |
5 |
60 - 75% |
Surgery (Lobectomy or Total Thyroidectomy) ±
Afirma |
|
Malignant |
6 |
99% |
What Is Molecular testing for Thyroid Nodules?
PACSO is the first, and currently the only unit in South Africa offering the Afirma test for thyroid nodules. This is an internationally validated molecular assay for thyroid nodules.
Thyroid nodules are very common and are seen in up to 60% of adults. The decision to treat with thyroid surgery is straightforward if the FNA results are positive for thyroid cancer. Similarly, surgery can usually be avoided if the biopsy results are benign.
However, in 10-20% of cases, the cytology is indeterminate making the decision to refer to surgery more difficult. The risk of thyroid cancer in nodules with indeterminate biopsy results varies a between 10-30%, but cannot be ignored.
In the past, to avoid missing a cancer, we recommended thyroid lobectomy (removal of half of the thyroid) to establish a definitive diagnosis. Now, we use molecular profiling. Afirma is a commercial RNA tests made specifically for thyroid nodules. If the genetic profile appears benign, patients can avoid surgery.
In cases where the molecular profile shows a risk for cancer, the test might further predict how aggressive the cancer is and the risk of spread to lymph nodes. It can also identify less common types of thyroid cancer, like Medullary cancer.
Thyroid Molecular Markers Allow Patients To Avoid Surgery
We want to help patients find that perfect balance between under-treatment and over-treatment. The people-gram shows how molecular testing can help patients avoid unnecessary surgery.
In the past, 75% of patients undergoing surgery for Bethesda III or IV nodules, was found not to have cancer.
With molecular testing, more than 50% of patients are categorized as benign, they can safely avoid surgery. Of the surgical patients who received a high risk molecular test result, cancer was found in more than 50% of those patients tested.
Surgery for thyroid nodules?
Thyroid lobectomy
A thyroid lobectomy or Diagnostic Lobectomy is an operation done under general anaesthetic, which involves removing approximately half of the thyroid gland (one lobe). This allows definitive diagnosis and in some cases treatment for thyroid cancer. During the procedure the portion of the thyroid that contains a concerning nodule is removed. Thyroid lobectomy is the procedure of choice for cases where:
- FNA remains inconclusive / non-diagnostic after two aspiration attempts.
- Bethesda III and IV nodules
For more information, click here
Total Thyroidectomy
A total thyroidectomy removes the entire thyroid gland. This surgery is appropriate when:
- Thyroid cancer has been diagnosed.
- Large multinodular thyroids
For more information, click here
