The thyroid is a part of the endocrine system. It is a small, butterfly-shaped gland at the base of the throat. It has a left lobe and a right lobe. The middle of the thyroid gland, where the lobes meet, is called the isthmus. The thyroid makes the hormone thyroxine. This helps the body regulate metabolism, blood pressure, heart rate, body temperature, and weight.
Thyroid cancer is the most common type of endocrine cancer. Diagnosis is on the rise in the United States. This may because it has become easier to find the disease. The National Cancer Institute (NCI) estimates that more than 56,000 new cases will be diagnosed in 2012. Thyroid cancer is also projected to cause more than 1,700 deaths.
Types of Thyroid Cancer and Incidence
Thyroid cancers are classified according to microscopic appearance. The types of thyroid cancer include:
Papillary thyroid cancer is a well-differentiated form of thyroid cancer. It’s the most common type of thyroid malignancy. It occurs in 80 percent of cases. It’s most often seen in women of childbearing age. Papillary thyroid cancer is less dangerous than the other types. It spreads more slowly. It is very treatable.
Medullary thyroid cancer is another well-differentiated form of thyroid cancer. It accounts for five to 10 percent of all thyroid cancers. Some cases of medullary thyroid cancer have a genetic component. This can cause it to occur as part of a syndrome of endocrine gland cancers. Cases without a genetic component are said to be “sporadic.”
Medullary thyroid cancer arises in non-thyroid cells that are located within the thyroid gland. It’s treated differently than other forms of thyroid cancer.
Follicular thyroid cancer occurs in 10 percent of cases. It’s the type of thyroid cancer most likely to spread and recur. Hurthle cell cancer is a type of follicular cancer.
This is the most aggressive form of thyroid cancer. It’s rare and difficult to treat.
This is a rare type of thyroid cancer. It begins in immune cells located within the thyroid gland.
Risk Factors for Thyroid Cancer
Risk factors for thyroid cancer include:
- family history of thyroid cancer
- age—thyroid cancer is most likely to occur after age 40
- female gender
- history of radiation exposure
Symptoms of Thyroid Cancer
Early thyroid cancer has no symptoms. Normally, the thyroid gland can’t be felt. As thyroid cancer progresses, the following symptoms may occur:
- a lump in the throat
- pain in the throat and neck
- difficulty swallowing
- swollen lymph nodes in the neck
If you have these symptoms, talk to your doctor.
Diagnosing Thyroid Cancer
Thyroid cancer may be diagnosed by physical exam or laboratory test. An examination of the neck may reveal a small or large mass in the thyroid. Lymph nodes may also be enlarged.
Lab tests that are used to diagnose thyroid cancer include:
- thyroid function tests (T4, T3RU, TSH)
- thyroglobulin, for papillary or follicular cancers
- ultrasound of the thyroid
- thyroid scan
- thyroid biopsy
- calcium, phosphorus levels in the blood
- calcitonin levels in the blood
- laryngoscopy can be used to look for cancer spread
Treatment of Thyroid Cancer
Treatment varies with the type of thyroid cancer. If the cancer has spread, or metastasized, this will affect treatment.
Most patients undergo surgical removal of all or part of the thyroid gland. Thyroid hormone can then be replaced with supplements.
Other treatment methods include:
- radioactive iodine
- external beam radiation therapy
What is the Prognosis of Thyroid Cancer
Prognosis for thyroid cancer is generally good. However, thyca.org estimates that thyroid cancer has a 30 percent recurrence rate.
Thyroid cancer can recur decades after initial treatment. Therefore, regular follow up is an essential part of care.