The most common types of thyroid cancer
Papillary carcinoma – the most common form of thyroid cancer, which accounts for 70 to 80 per cent of cases
- This cancer affects the cells that produce thyroid hormone
- It grows slowly
Follicular carcinoma – this cancer also affects thyroid hormone-producing cells
- However, it grows more quickly
- Follicular cancer accounts for around 10 per cent of thyroid cancers
Medullary carcinoma – this type of cancer tends to run in families
- The symptoms may mimic those of Cushing’s syndrome
- It does not involve thyroid hormone-producing cells and accounts for 5 to 10 per cent of thyroid cancers
Anaplastic carcinoma – this is the most aggressive and malignant form of thyroid cancer
- It tends to grow rapidly and block the windpipe
- It generally originates in benign or low grade cancerous thyroid tumours and accounts for around 7 per cent of thyroid cancers
Thyroid lymphoma – this occurs when white blood cells (lymphocytes) invade the thyroid and become cancerous
- This accounts for around 4 per cent of thyroid cancers
An appreciation of the classification of thyroid cancer is important as there is a wide range of growth and behaviour
- The degree of malignancy of the different types of thyroid cancer is often categorized according to their “differentiation”
- The more differentiated the thyroid cancer is, the more it resembles the normal thyroid tissue, and therefore the more treatable the tumour
- Papillary and follicular cancers are “well differentiated” thyroid cancers and account for about 90% of cases and are usually associated with the best outcomes
- At the other extreme is undifferentiated carcinoma which usually appears late in life and is invasive – most patients with anaplastic thyroid carcinoma succumb from local disease or pulmonary metastases or both
- Between the two extremes are follicular and medullary carcinomas, sarcomas, lymphomas and secondary tumours
- Medullary thyroid cancer is not classified according to its differentiation because it does not arise from thyroid cells, but rather from “C” cells which are neuroendocrine cells within the thyroid
- Thyroid lymphoma is very uncommon but can be confused with anaplastic cancer because it tends to grow rapidly and cause symptoms like difficulty breathing or problems with eating and drinking – fortunately, thyroid lymphoma is very treatable and therefore must be differentiated from anaplastic cancer
If you have any questions about thyroid or parathyroid surgery, you should speak to your local doctor, who will arrange to contact your thyroid surgeon.
