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Maurie Markman, MD, President, Medicine & Science.
This page was updated on June 7, 2022.
There are several types of thyroid cancer, which are classified based on how similar they look to normal thyroid cells under a microscope (differentiated vs. undifferentiated) and by the type of cell from which they develop. The four primary types of thyroid cancer are follicular, papillary, anaplastic and medullary.
Papillary thyroid cancer, or papillary carcinoma, is the most common type of thyroid cancer, accounting for approximately 80 percent of cases. Papillary carcinomas are slow-growing, differentiated cancers that develop from follicular cells and can develop in one or both lobes of the thyroid gland. This type of cancer may spread to nearby lymph nodes in the neck, but it is generally treatable with a good prognosis (outlook for survival).
Follicular thyroid cancer, or follicular carcinoma, is the second most common type of thyroid cancer, and accounts for approximately one out of 10 cases. It is found more frequently in countries with an inadequate dietary intake of iodine. Follicular carcinoma is also a differentiated form of thyroid cancer. In most cases, it is associated with a good prognosis, although it is somewhat more aggressive than papillary cancer. Follicular carcinomas do not usually spread to nearby lymph nodes, but they are more likely than papillary cancers to spread to other organs, like the lungs or the bones.
Hürthle cell thyroid cancer, also known as Hürthle cell carcinoma and oxyphil cell carcinoma, is a rare thyroid cancer. This subtype of follicular carcinoma accounts for approximately 3 percent of all thyroid cancers.
Medullary thyroid cancer, or medullary thyroid carcinoma, develops from C cells in the thyroid gland, and is more aggressive and less differentiated than papillary or follicular cancers. Approximately 4 percent of all thyroid cancers will be of the medullary subtype. These cancers are more likely to spread to lymph nodes and other organs, compared with the more differentiated thyroid cancers. They also frequently release high levels calcitonin and carcinoembryonic antigen (CEA), which can be detected by thyroid blood tests.
Anaplastic thyroid cancer, or anaplastic thyroid carcinoma, is the most undifferentiated type of thyroid cancer, meaning that it looks the least like normal cells of the thyroid gland. As a result, it is a very aggressive form of cancer that quickly spreads to other parts of the neck and body. It's a rare thyroid cancer that occurs in approximately 2 percent of thyroid cancer cases.
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