The thyroid is a butterfly-shaped organ located in the neck in front of the trachea (wind pipe). According to the Mayo Clinic, the thyroid produces hormones that help regulate the body's temperature, blood pressure, and metabolism. The National Cancer Institute adds that 37,200 people in the U.S. are diagnosed annually with thyroid cancer, but only about 4 percent of thyroid cancers are fatal.
Papillary Carcinoma
Merck Manuals, an online medical library, reports that papillary carcinoma is the most common type of thyroid cancer: approximately 70 to 80 percent of thyroid cancers are of this type. The American Cancer Society indicates that this type of cancer usually grows very slowly, but often spreads to the nearby lymph nodes. Commonly, papillary carcinoma is mixed with follicular carcinoma. Whether mixed with follicular carcinoma or not, the prognosis of papillary carcinoma tends to be very good and treatment is usually successful. Other subtypes, including columnar, tall cell, and diffuse sclerosis, may spread more quickly, and thus have a poorer prognosis. All types of thyroid cancer are diagnosed based upon their appearance under a microscope. Papillary carcinoma most often affects people between the ages of 30 and 50.
Follicular Carcinoma
Follicular carcinoma usually affects people older than 50, according to the Mayo Clinic. The American Cancer Society reports that this is the second most common type, making up about 10 percent of thyroid cancers. Follicular carcinomas usually do not spread to the lymph nodes like papillary carcinoma but can spread to other sites of the body. The prognosis of this type of thyroid cancer is slightly less optimistic than papillary carcinoma, but it is generally still quite treatable. One subtype of follicular carcinoma is Hurthle cell carcinoma, which makes up about 4 percent of cancers affecting the thyroid. This type of thyroid cancer is harder to treat than other types because it does not readily absorb radioactive iodine, the common treatment for cancers of the thyroid.
Medullary Thyroid Cancer
Merck Manuals notes that medullary thyroid cancer is relatively uncommon, making up about 3 percent of all thyroid cancers. This cancer arises from a type of thyroid cell called a parafollicular cell or C cells; these cells produce a hormone called calcitonin. This type of cancer has a strong genetic component, meaning that your risk of acquiring medullary thyroid cancer is much higher if you have an immediate family member who has the disease.
Anaplastic Carcinoma
Anaplastic carcinoma is also quite rare, accounting for 2 percent of all thyroid cancer, and most often affects the elderly. The anaplastic carcinoma tumor grows rapidly, causing a very painful lump in the neck. This is a very severe form of thyroid cancer with a poor prognosis, causing death in 80 percent of patients within one year of diagnosis.
