Thyroid cancer affects the thyroid gland, which is located in the front part of the neck and below the thyroid cartilage (or Adam’s apple). The thyroid gland produces hormones that help regulate heart rate, blood pressure, metabolism and body temperature.
The thyroid gland is made up of two main types of cells:
Follicular cells produce thyroid hormones. Hyperthyroidism is a condition in which two much thyroid hormones are produced, causing symptoms such as difficulty sleeping, nervousness, hunger, weight loss, fast or irregular heartbeat, and a feeling of being too warm. Hypothyroidism is a condition in which too little hormones are produced, causing an individual to feel tired and gain weight. The amount of thyroid hormone released by the thyroid is regulated by the pituitary gland, which produces thyroid-stimulating hormone (TSH).
C cells produce calcitonin, a hormone that helps control the body’s use of calcium. The thyroid gland also contains immune system cells (called lymphocytes) and supportive (stromal) cells.
Types of Thyroid Cancers
The three main types of thyroid cancers are:
- Differentiated (papillary, follicular and Hürthle cell)
- Anaplastic (an aggressive cancer)
Papillary thyroid cancer is the most common type of thyroid cancer and typically affects people ages 30 to 50. Follicular thyroid cancer typically affects people over the age of 50. Hürthle cell cancer is a rare and more aggressive type of follicular cancer.
Anaplastic thyroid cancer is a rare form of thyroid cancer that begins in the follicular cells, grows rapidly and is difficult to treat. This type of cancer is most common in adults ages 60 and older.
Medullary thyroid cancer forms in the C cells and may cause elevated levels of calcitonin in the blood. Other rare forms of thyroid cancer include thyroid lymphoma and thyroid sarcoma.
Signs of thyroid cancer include:
- Difficulty swallowing
- Pain in the neck and throat
- Changes to the voice
- Swollen lymph nodes in the neck
- A lump that can be felt through the skin on the neck
Thyroid cancer may return even if the thyroid has been removed. Recurring cancer may be found in:
- Lymph nodes in the neck
- Small pieces of thyroid tissue left behind during surgery
- Distant areas of the body, such as the lungs and bones
The following factors increase an individual’s risk of developing thyroid cancer:
- Being female
- Exposure to high levels of radiation
- Certain inherited genetic syndromes such as familial medullary thyroid cancer, multiple endocrine neoplasia, familial adenomatous polyposis and Cowden’s syndrome
Diagnosing Thyroid Cancer
To diagnose thyroid cancer, the physician may perform the following tests and procedures:
- Physical exam to check for physical changes in the thyroid
- Blood tests to check if the thyroid gland is functioning properly
- Imaging tests, such as ultrasound, CT, MRI and nuclear imaging
- Biopsy, such as a fine-needle aspiration biopsy
- Genetic testing if the patient has a family history of conditions that increase the risk of thyroid cancer
Thyroid cancer may be treated by removing all or most of the thyroid (thyroidectomy), removing a portion of the thyroid (thyroid lobectomy) or removing lymph nodes in the neck (lymph node dissection).
Other treatment options include thyroid hormone therapy, chemotherapy, external radiation therapy, targeted drug therapy, alcohol ablation and radioactive iodine treatment.