Douglas A. Nelson, MD, is a board-certified oncologist and hematologist who previously served for 13 years as a physician in the US Air Force.
Thyroid cancer is cancer of the thyroid gland in the neck. It is the fifth most common type of cancer in women in the United States. The increase is attributed to earlier diagnosis due to more sensitive imaging tests. Thyroid cancer affects women more often than men. It has a good prognosis. Risk factors include family history of this cancer, radiation exposure, and low dietary iodine.
Thyroid cancer may be detected incidentally with imaging studies done for another indication, or it can cause a visible neck lump. This cancer is diagnosed with imaging tests, such as thyroid ultrasound, and a needle biopsy. Treatment can include surgery, radioactive iodine, chemotherapy, radiation, and targeted therapy. Thyroid hormone replacement medication is usually needed after the thyroid gland is removed.
Thyroid cancer is caused by alterations and overgrowth of thyroid tissue. There are several types of thyroid cancer, each originating in a different type of thyroid cell. The overgrowth occurs due to hereditary or acquired mutations (genetic changes). Risk factors associated with these changes include radiation exposure, low dietary iodine, and inherited conditions.
Thyroid cancer is often asymptomatic. Symptoms are usually related to the tumor pressing on the trachea (windpipe) or esophagus (food pipe) and include a visible neck growth, trouble swallowing, hoarse voice, coughing, and/or neck discomfort. Thyroid cancer is not associated with hormone changes, but many other cancers are linked with thyroid hormone alterations.
Thyroid cancer has the potential to spread, but local growth of the tumor within the thyroid gland is more common than metastasis. All of the types of thyroid cancer can metastasize to other areas of the body, causing symptoms such as shortness of breath or bone pain. Metastases are associated with a lower chance of cure and survival.
Thyroid cancer can be hereditary or acquired. Associated familial diseases have their own inheritance pattern, and some have known gene defects. They include familial medullary thyroid carcinoma (RET gene), familial adenomatous polyposis (APC gene), Cowden disease (PTEN gene), Carney complex type 1 (PRKAR1A gene), nonfamilial medullary thyroid carcinoma, and multiple endocrine neoplasia type 2.
Thyroid cancer treatment is tailored to the type and stage. Active surveillance is an option when the tumor is small and benign. Treatments include radioactive iodine therapy, radiation, chemotherapy, alcohol ablation, or targeted drug therapy. Surgery may include lobectomy, thyroidectomy and/or lymph node removal. Thyroid hormone replacement is needed after the removal of the thyroid gland.
Anaplastic thyroid cancer, a rare type, is highly aggressive. Only 50% of people with anaplastic thyroid cancer survive longer than six months.1 It is associated with non-hereditary gene mutations and is often preceded by another type of thyroid cancer or radiation exposure. It is also described as undifferentiated thyroid cancer due to the severely altered appearance of the cancer cells.
Follicular thyroid cancer is the second most common type of thyroid cancer, after papillary type. This is a slow-growing tumor that forms a lump in the throat. It is usually treated with surgery and radioactive iodine and has a 98% survival rate.
Medullary thyroid cancer, an uncommon type, may begin with a lump in the neck. It can grow rapidly and metastasize. It begins in the parafollicular C cells of the thyroid gland, which produce calcitonin, a calcium-regulating hormone. It is usually treated with complete thyroidectomy, followed by radiation, chemotherapy, and/or targeted treatment and continued long-term monitoring.
Nodules are growths on part of the body. They can be hard or fluid-filled. Thyroid nodules are usually benign, but they can be cancerous tumors. Sometimes a nodule is examined with imaging and/or biopsy to determine whether it has the potential to be harmful.
Papillary thyroid cancer is the most common type of thyroid cancer. It is slow-growing and can invade nearby lymph nodes. This cancer is often associated with genetic mutations and familial diseases. Treatment includes surgical removal of the tumor and radioactive iodine. When treated, the prognosis is very good.
Radiation therapy is used to treat a number of diseases that are associated with overgrowth of tissue or abnormal tissue growth, including cancer. Radiation therapy is a risk factor for thyroid cancer, and it is also one of the treatments for thyroid cancer. Radioactive iodine destroys thyroid tissue, and it is used to treat thyroid cancer and certain overactive thyroid conditions.
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American Thyroid Association. Thyroid cancer. Updated October 2019.
American Cancer Society. Thyroid cancer survival rates, by type and stage. Updated January 9, 2020
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National Cancer Institute. Anaplastic thyroid cancer. Updated February 27, 2019.
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