Thyroid cancer, also called thyroid carcinoma, is a malignant tumour of the thyroid.

Thyroid Cancer Types

The treatment and course of the disease depend on the type of thyroid cell the cancer originates from. Thyroid cancer affects more women than men and the average age at diagnosis is 45-50 years.

Differentiated carcinomas

Differentiated carcinomas are the most common type of thyroid cancer (>90% of cases) and include papillary and follicular types. Their cell structures most closely resemble that of normal thyroid tissue, so they are usually less aggressive.  Like normal thyroid tissue, differentiated thyroid carcinoma cells have the ability to take up iodine and can be selectively treated with surgery followed by therapy with radioactive iodine. 

Medullary carcinomas

Medullary carcinomas account for <5% of all thyroid carcinomas. This type of thyroid cancer is often genetic and originates from the so-called parafollicular cells (C cells). Found in small clusters in the thyroid, these are cells that produce the hormone calcitonin which is especially important for bone health.

Undifferentiated or anaplastic carcinomas

Undifferentiated or anaplastic carcinomas are one of the rarer forms of thyroid cancer, accounting for around 1% of cases. This is the most aggressive form of thyroid cancer and neighbouring organs are often already affected by the time it is diagnosed.

Medullary Thyroid Cancer

Medullary thyroid cancer (MTC) accounts for around 1-2% of all thyroid cancers and it can affect people of all ages. MTC is different from other types of thyroid cancer because it develops in the parafollicular cells (commonly called ‘C’ cells) of the thyroid, which have features of both endocrine cells (which relate to hormones) and neurological cells (which relate to the nervous system).

C cells produce a hormone called calcitonin which affects the regulation of calcium in the body, and which is especially important for bone health.