Thyroid cancer refers to a condition in Singapore where rogue cells in the thyroid produce at a rate beyond which the immune system can manage. It first presents as a tumour or nodule in the thyroid gland — a small butterfly-shaped gland located near your voice box and in front of your windpipe, at the base of your neck and just above your breastbone.
In Singapore, thyroid cancer is the eight most common cancer amongst women, with about 1,100 cases reported every year. Worldwide, thyroid cancer is the most common endocrine malignancy. This could be due to late detection as thyroid cancer often presents with unnoticeable symptoms until the tumour or nodule grows to a sizeable state.
There are several types of thyroid cancer, classified according to the kinds of cells found in the tumour. The two most common types of thyroid cancer are papillary thyroid cancer and follicular thyroid cancer, accounting for about 95% of cases.
Other types of cancer include medullary thyroid cancer and anaplastic thyroid cancer, and the fairly rare thyroid lymphoma and thyroid sarcoma.
There is no definite evidence to explain what causes thyroid cancer.
What is known is that thyroid cancer occurs when the cells in your thyroid mutate, and these mutated cells multiply rapidly. As a result of these mutations, the cells become more hardy and do not die the way normal cells do. The accumulation of abnormal cells in the thyroid forms a tumour or nodule. These cells can then invade nearby tissue and spread to other parts of the body.
The thyroid is in charge of producing hormones responsible for regulating body temperature, heart rate, blood pressure, and weight. In the early stages of thyroid cancer, you may not notice any visible changes. However, as it grows, you may feel a lump more obviously in your neck. Other symptoms include:
As the tumour grows, it can result in some pain in the neck and throat where the tumour is.
Factors that may increase the risk of thyroid cancer include:
To diagnose thyroid cancer, your doctor will carry out what’s called a Fine Needle Aspiration Biopsy (FNAB). You will lie on your back with your head tipped backwards. Ultrasound will be used to guide the accurate placement of the needle, so as to draw a sample of the tumour.
The procedure itself would take about 10 minutes and the sample drawn can be examined under a microscope immediately for a faster diagnosis, or the sample may be sent to a laboratory for testing.
Between 1% to 2% of the population will get thyroid cancer at some point during their lifetime. The treatment plan would depend on the stage of cancer with the early stage being the easiest to treat and the advance stage more challenging. People diagnosed with thyroid cancer at the age of below 45 usually means the disease is in an early stage. Other factors to consider include the size of the tumour and the extent of spread.
Surgical removal of part (hemithyroidectomy) or the whole (total thyroidectomy) thyroid gland, including the surrounding lymph nodes, will be considered. Surgical removal of the whole gland is normally the preferred option, especially for people with early stage disease, as the endocrinologist will be able to check for possible recurrence of the cancer.
The traditional approach to surgery is an open surgery. However, new techniques exist today that are less invasive but equally effective. Endoscopic thyroidectomy and robot-assisted thyroidectomy are both techniques that involve the use of small incisions in the armpit or chest, instead of the neck to avoid a surgical scar on the neck.
Patients with papillary or follicular thyroid cancer may receive radioiodine treatment about 4 weeks post-surgery. This treatment involves drinking a small amount of solution with radioactive iodine, usually just once. Radioiodine eliminates any thyroid tissue that may still be left. After this treatment, a full-body radionuclide scan is carried out to confirm that there is no thyroid tissue left in the body. This is followed by a lifelong thyroid hormone replacement treatment, to provide our body with the hormones it needs and prevents thyroid cancer from recurring. Patients who are in complete remission will need to have their thyroid function and serum thyroglobulin checked every half-yearly.
Despite treatment, there is a chance that cancer might recur. This can happen when cancer cells spread beyond the thyroid, before it is removed. Recurring cancer cells can, fortunately, be treated.