Thyroid cancer

Clinical picture

Thyroid cancer occurs in the cells of the thyroid – a butterfly-shaped gland located at the base of your neck, just below the Adam's apple. The thyroid produces hormones that regulate heart rate, blood pressure, body temperature and weight. Thyroid cancer is one of the more curable types of cancer.

There are several types that can be identified:

Papillary thyroid cancer: this type affects around 75% of all thyroid cancer patients, and is typically a slow-growing tumour.
Follicular thyroid cancer affects roughly 15% of all thyroid cancer patients.

(Both these types – only microscopic research will tell them apart – grow from follicular cells in the thyroid, and both produce the thyroid hormone. They are relatively easy to treat with radioactive iodine.)

Medullar thyroid cancer develops in the C cells of the thyroid that are responsible for producing the hormone calcitonin, which plays part in regulating calcium levels in the blood. This is a more aggressive type of thyroid cancer that will also spread more than other types.
Anaplastic thyroid cancer affects 5% of thyroid cancer patients. This is the most dangerous type, spreading rapidly.

In Belgium, around 755 persons are diagnosed with thyroid cancer annually, and this cancer affects far more women than men. Patients are usually between 45 and 55 years old at the time of diagnosis. The outlook of thyroid cancer is quite good for stages I to III. The 5-year survival rate in these stages is between 98% and 92%. This percentage drops to 53% in stage IV.

Symptoms

Thyroid cancer is relatively rare, and growths in the thyroid often turn out to be benign. Patients that do suffer from thyroid cancer may experience symptoms such as:

a lump in the throat in the thyroid area
hoarseness
Short of breath/difficulty breathing
difficulties with swallowing
sore throat and coughing

Less frequent symptoms include:

headaches and neck pains
intestinal problems
excess saliva
muscular weakness
chest pains
palpitations
fatigue

Cause

A clear cause for thyroid cancer is as yet unknown, but certain risk factors have been identified. These include:

having had radiotherapy at an early age, especially of chest, neck or head
genetic disposition: in around 5% of patients, there is a genetic disposition for thyroid cancer (these are usually patients who get the disease at a young age, who have several family members with cancer or have the genetic disorder MEN2)
having been exposed to a large dose of radiation
having an enlarged thyroid

Diagnosis

A GP who suspects a patient may have thyroid cancer will perform a physical examination and possibly a blood test or an ultrasound. The patient will then be referred to an endocrinologist for further testing. These tests include blood tests, ultrasounds, biopsies, CT scans or MRI scans. If results remain inconclusive, a specialist may remove half of the thyroid for lab research.

Thyroid cancer is graded into four stages, following the TNM classification system.

Stage I: The tumour does not exceed 2 cm in diameter and is contained within the thyroid
Stage II: The tumour measures 2 to 4 cm in diameter and is contained within the thyroid
Stage III:
- The tumour exceeds 4 cm but is still contained within the thyroid
- The tumour has grown into surrounding tissue
Stage IV:
- IVa: The tumour has spread to the larynx, the skin, the oesophagus, the vocal chords or the trachea
- IVb: The tumour has spread to surrounding connective tissue, blood vessels or the spine. Only anaplastic tumours are capable of this degree of spreading

Treatment

After the diagnosis has been established, specialists will come up with a treatment plan. Thyroid cancer is commonly treated by surgery, radioactive iodine, radiotherapy or targeted therapy.

Papillary and follicular thyroid cancer can often be removed by means of surgery. The thyroid can be entirely or partially removed, depending on size and position of the tumour. In some cases, adjuvant therapy with radioactive iodine is deemed necessary. Patients who undergo this treatment make a full recovery and have no recurrence.

Patients with a medullar carcinoma are usually treated by surgery and radiation, depending on size and location of the tumour. The outlook depends on the tumour stage. Patients with anaplastic thyroid cancer are generally beyond healing: they receive palliative care. This can include targeted therapy with kinase, RET or BRAF/MEK inhibitors that specifically hamper the growth rate of the tumour.