Thyroid cancer develops in your thyroid gland. Many thyroid gland growths and tumors are non-cancerous, benign. But many are malignant cancers that can spread to other parts of your body. Malignant thyroid cancers include:
Most thyroid cancer diagnoses are for differentiated cancers, with cells looking under the microscope much like healthy thyroid tissue. Differentiated cancers in the thyroid gland develop from follicular cells and include papillary cancer, follicular cancer and Hurthle cell cancer.
Papillary cancer accounts for about 80 percent of all thyroid cancers. These grow slowly, developing in only one of the thyroid’s lobes. Despite being slow-growing and rarely fatal, papillary cancers frequently spread into neck lymph nodes. Subtypes of papillary cancer include:
Follicular cancer of the thyroid makes up about ten percent of thyroid cancer diagnoses. This type usually spreads to lungs, bones and other parts of the body except the lymph nodes. The outlook for this type of thyroid cancer is still very good, although not as positive as for papillary differentiated cancers of the thyroid.
Hurthle cell cancer, also called oxyphil cell carcinoma, makes up about three percent of thyroid cancers. This cancer provides a less positive outlook than other differentiated thyroid cancers.
Medullary thyroid carcinoma makes up about four percent of thyroid cancers, developing from the thyroid gland’s C cells, those making calcitonin hormone controlling your blood calcium levels. This cancer sometimes spreads to your lymph nodes, liver or lungs, before finding the first nodule.
There are two difficult-to-treat types of medullary thyroid carcinoma:
Anaplastic carcinoma only makes up about two percent of all thyroid cancer diagnoses. This cancer sometimes develops from other types of thyroid cancer, with its cells not looking like normal thyroid cells. Anaplastic undifferentiated thyroid cancer spreads quickly and proves difficult to treat.
About four percent of thyroid cancers include thyroid lymphomas, thyroid sarcomas or other rare types of cancer. One extremely rare thyroid tumor is parathyroid cancer. This cancer actually affects the four tiny glands behind the thyroid. In the U.S. each year, fewer than 100 people experience a diagnosis of parathyroid cancer.