Thyroid cancer is the twelfth most common cancer in the United States. In 2018, it's estimated that approximately three percent of all new cancer cases were thyroid cancer, and, according to the American Cancer Society, there will be more than 52,000 new cases of thyroid cancer in the United States in 2019. The prevalence of thyroid cancer is nearly three times higher in women than men, and nearly twice as high in Caucasians than African Americans, with people of Asian and Pacific Islander descent having the second highest incidence rate.
There are four types of thyroid cancer:
- Papillary thyroid cancer- the most common type, accounting for approximately 80 percent of all cases, can occur at any age and tends to grow slowly, often spreading to lymph nodes in the neck.
- Follicular thyroid cancer- forms in the follicular cells in the thyroid and tends to occur in older patients, accounting for about 10 to 15 percent of all cases.
- Medullary thyroid cancer- develops in the C cells of the thyroid (the cells that make the hormone calcitonin, which helps maintain blood calcium levels).
- Anaplastic thyroid cancer- a rare, aggressive type of thyroid cancer with the poorest prognosis.
Signs and Symptoms of Thyroid Cancer
Thyroid cancer may not have early signs. As the tumor grows, it can cause symptoms such as the following:
- A lump or swelling in the neck
- Trouble breathing
- Trouble swallowing
- Hoarseness in the throat
To check for thyroid cancer, the following tests and procedures may be used:
- Physical exam and review of medical history.
- Laryngoscopy: checks the larynx (voice box) and the movement of the vocal cords.
- Blood hormone studies: measures the amounts of certain hormones including thyroid-stimulating hormone (TSH), calcitonin and antithyroid antibodies
- Blood chemistry studies.
- Radioiodine scan of the thyroid: a camera is placed in front of the neck to measure the amount of radiation in the thyroid. This test can find nodules in the thyroid gland that may need further evaluation.
- Ultrasound:shows the size and type of a thyroid tumor and guides a fine-needle aspiration biopsy.
- Fine-needle aspiration biopsy: removes a tissue sample to check for cancer cells.
- CT scan (CAT scan): provides a series of detailed pictures of specific areas inside the body
- Surgical biopsy: removes the thyroid nodule or one lobe of the thyroid during surgery so the cells and tissues can be viewed under a microscope by a pathologist.
Because the type of thyroid cancer can be hard to diagnose, biopsy samples should be checked by a pathologist who has experience diagnosing thyroid cancer.
Risk Factors for Thyroid Cancer
Although there are no routine screening tests for thyroid cancer, there are factors that can increase the risk of developing the disease. These include:
- Exposure to radiation to the head and neck as a child.
- Exposure to radioactive fallout.
- Personal history of goiter.
- Being female.
- Being between 25 and 65 years old.
- Family history of thyroid disease or thyroid cancer.
- Certain genetic conditions such as familial medullary thyroid cancer (FMTC), multiple endocrine neoplasia type 2A syndrome and multiple endocrine neoplasia type 2B syndrome.