What are thyroid cancers?

The thyroid is an endocrine gland that produces thyroid hormones, which affect energy and heat production, metabolism, heart rate and more. Researchers estimate France had nearly 7,700 new cases of thyroid cancer in 2023¹, occurring more often in women (73% of new cases).

Institut Curie is an expert center within TUTHYREF (the Refractory Thyroid Tumors Network), which brings together endocrinologists, oncologists, surgeons, and pathologists to improve care for patients with refractory thyroid cancers. Established in 2009, the network is supported by the French National Cancer Institute (INCa).

Cancers of the thyroid, which is located in front of the neck just above the larynx, develop from a thyroid cell that mutates and multiplies uncontrollably. 

There are two main types of thyroid cancer, originating from two different types of cells: follicular-derived thyroid cancer and medullary thyroid cancer. 

• Follicular-derived thyroid cancers, which are the most common, originate in thyrocytes, the cells that produce thyroid hormones. 
  Over 90% of follicular-derived thyroid cancers are differentiated, meaning their cells retain features similar to normal tissue, and they tend to grow slowly. These cancers have an excellent prognosis and additionally can absorb iodine, which is useful for treatment. They include two main subtypes: papillary (75%) and follicular (15%). 
  About 5% of follicular-derived thyroid cancers are poorly differentiated, meaning they grow more quickly and are more serious. Very rare serious andancers are undifferentiated, extremely serious and require urgent treatment. In France, fewer than 100 new cases of anaplastic cancer are diagnosed annually.
• Medullary thyroid cancers develop from cells around the follicles. These are known as C cells because they produce calcitonin, a hormone that regulates phosphorus and calcium metabolism. 
  Some people have a genetic predisposition to these rare cancers, which account for 5% of all thyroid cancers and which vary in severity.  

Risk factors for thyroid cancer

There are few risk factors for thyroid cancer. The vast majority of thyroid cancers have no identified risk factor. The most recognized risk factor is a history of childhood radiotherapy, although modern techniques minimize thyroid exposure to radiation. Physicians are especially careful to monitor patients in their 20s who have been treated for conditions such as leukemia.

Certain genetic disorders may also increase risk, but they are rare. Some, such as Cowden syndrome (caused by a mutation in the PTEN gene) or the DICER1 gene mutation, increase the risk of differentiated follicular-derived thyroid cancers. In addition, a mutation of the RET gene appears to promote development of medullary thyroid cancer. 

[1] Source: French National Cancer Institute (INCa)