Thyroid cancer is cancer that occurs from the thyroid gland, and is more prominent in women than men. In Singapore, thyroid cancer is the 9th most common cancer among women. While people are more likely to develop thyroid nodules as they age, thyroid cancer is diagnosed at a younger age compared to other cancers. Most cases also occur in patients below 60 years old.
The rates of thyroid cancer appear to be rising in Singapore, but this could be due to an increased use of ultrasound scans which are able to pick up thyroid nodules that may have not been discovered in the past.
Regardless, it’s good that we have advancements in medicine that help bring awareness to thyroid cancer as this condition often come with no symptoms, making it a silent killer.
To date, we still don’t know what causes thyroid cancer, but we know that it occurs when cells in the thyroid undergo genetic mutations. These mutations allow cells to multiply and accumulate in size rapidly, forming a tumour.
There are certain groups that are at risk of developing thyroid cancer:
People who belong in these groups should take extra care and go for scans during their annual checkups whenever possible.
Thyroid cancer typically does not carry any symptoms, especially in the early stages. As the cancer grows, it may cause:
The type of thyroid cancer depends on the kind of cells found in the tumour. This is determined when a sample of cell tissue is examined by your doctor.
The types of thyroid cancer include:
Papillary thyroid cancer
This is the most common form of thyroid cancer and accounts for about 75% of thyroid cancers. Papillary thyroid cancer grows from follicular cells, which store and produce thyroid hormones. It is slow growing but can spread to the lymph nodes in the neck. Papillary thyroid cancer occurs at any age, but tend to affect people from ages 30 to 50.
Follicular thyroid cancer
Follicular thyroid cancer is the second most common type of thyroid cancer and accounts for about 15% of cases. This cancer also arises from the follicular cells and usually affects individuals over 50 years old. In most cases, the cancer tends to spread via the bloodstream to parts of the body like the bones and lungs.
Medullary thyroid cancer
Medullary thyroid cancer grows from the parafollicular C cells in the thyroid gland. C cells produce a hormone called calcitonin, which controls calcium levels in the body. About 20% of medullary thyroid cancer cases are hereditary, and these patients tend to develop thyroid cancers as early as childhood. They may also develop other types of cancers.
Anaplastic thyroid cancer
Anaplastic thyroid cancer accounts for about 2% of thyroid cancer cases. It grows aggressively and spreads rapidly to other parts of the body. Anaplastic thyroid cancer usually occurs in patients above 60 and is very hard to treat.
Thyroid lymphoma is a very rare cancer that arises from the immune system cells of the thyroid gland. It Is usually treated with chemotherapy.
Thyroid cancers are usually treated through surgery, and may include one or more of the following procedures:
A thyroidectomy involves removing part of or the whole thyroid gland. Depending on the type of cancer, patients can choose to remove only half of the thyroid gland. This is known as a hemi-thyroidectomy.
Central compartment dissection
A central compartment dissection is usually recommended for patients with medullary and papillary thyroid cancer, where the cancer spreads to the lymph nodes around the thyroid gland. These lymph nodes, together with the thyroid gland and trachea may be removed.
Modified radical neck dissection
When thyroid cancer spreads to lymph nodes at the side of the neck and in the neck, the affected and cancerous lymph nodes may be removed.
Radioactive iodine treatment
This treatment, which uses a radioactive form of iodine, selectively administers radiation to thyroid cancer cells. It’s usually used on follicular and papillary thyroid cancers as these cancers react to iodine well.
External beam radiotherapy
Through this treatment, ionising radiation is used to kill cancer cells. It is used in cases where surgery is unable to remove the cancer completely, or in cases where the cancer cells do not react to iodine, such as in anaplastic and medullary thyroid cancers.