Thyroid cancer is a rare type of cancer that affects the thyroid gland, a small butterfly-shaped gland located at the base of the neck. The cause of thyroid cancer is not well understood, but it may involve a combination of genetic and environmental factors. People with thyroid cancer may not have any symptoms, but some may notice a lump in the neck. Treatments for thyroid cancer are generally successful and include surgery, hormonal therapy, radioactive iodine, radiation, and in some cases chemotherapy. Thyroid nodules are often discovered accidentally on imaging tests such as CT scans and neck ultrasounds.
You may also find a thyroid nodule by noticing a lump in your neck while looking in a mirror, buttoning your shirt, or fastening a necklace. Rarely, cancers and thyroid nodules can cause symptoms such as pain in the neck, jaw, or ear. If a lump is large enough to compress the trachea or esophagus, it can cause difficulty breathing, swallowing, or a “tickling” sensation in the throat. Even less often, you can develop hoarseness if thyroid cancer invades the nerve that controls the vocal cords. For information on childhood thyroid cancer, see the PDQ summary on Childhood Thyroid Cancer Treatment.
Because only thyroid tissue absorbs iodine, radioactive iodine (RAI) destroys thyroid tissue and thyroid cancer cells without damaging other tissues. This helps explain the high number of people diagnosed with thyroid cancer and overall survival rates. Anaplastic thyroid cancer is the most advanced and aggressive type of thyroid cancer and is least likely to respond to treatment. Differentiated thyroid cancers (DTCs) are treated by a combination of surgery to remove the thyroid gland (thyroidectomy) and a type of radiation therapy that kills any remaining cancer cells and prevents thyroid cancer from returning. Your healthcare provider can discuss the best treatment option for the type of thyroid cancer you have.
Recent studies even suggest that if you have a small tumor that measures less than 1 cm in diameter, called papillary thyroid microcarcinoma, you may be seen very safely without surgery. If part or all of the thyroid gland is removed, it will no longer be able to produce hormones that regulate the metabolic system. It is estimated that between 5 and 20% of people with a history of thyroid cancer will experience a return of cancer cells in the neck. The extent of surgery will depend on the size of the tumor and whether or not the tumor has spread beyond the thyroid gland. Thyroid cancer can only be diagnosed with certainty after the nodule has been surgically removed (see the Thyroid Nodules brochure). Sometimes, a drug that blocks the effects of radiation on the thyroid is given to people who live near nuclear power plants in the United States.
With this information, doctors may decide to do a biopsy to remove a small sample of thyroid tissue.
