Welcome to the Patient Education Library of Texas Medical Institute
The exact cause of most thyroid cancers is unknown. Cancer occurs when cells grow abnormally and out of control, instead of dividing in an orderly manner. Thyroid cancer is more common in women than in men. It occurs most frequently between the ages of 20 and 60 years old.
Some cases of thyroid cancer may be linked to changes in DNA. Your DNA is the carrier of your genetic information, including directions for how your cells divide. You inherited your DNA from your parents. People with a family history of thyroid cancer have an increased risk for developing thyroid cancer.
Exposure to radioactivity from nuclear reactive material, nuclear plant accidents, or some types of radiation therapy for cancer can increase the risk for thyroid cancer. In some parts of the world, diets that are low in iodine increase the risk for thyroid cancer. This is not a concern in the United States, since iodine is contained in table salt and many of the foods we eat.
There are several types of thyroid cancer. Some of the more common types of thyroid cancer include:
The majority of thyroid cancers are papillary carcinomas. They occur most frequently in women of childbearing age. Papillary carcinoma originates in the thyroid follicle cells. It is generally a very slow growing cancer that may gradually spread to other parts of the body. Papillary carcinoma tends to spread to the lymph nodes in the neck, most of the time this is very treatable. Papillary cancer is the least likely type of thyroid cancer to cause death.
Follicular carcinoma is the second most common type of thyroid cancer. It is more common in countries where people do not eat enough iodine in their diets. This is not a common situation in the United States where people ingest iodine in table salt and food on a regular basis. Follicular carcinoma usually remains in the thyroid gland, but it may spread to the lungs and bone. Follicular carcinoma tends to return. Cancer that comes back after treatment is termed recurrent
Medullary carcinoma of the thyroid (MCT)
MCT develops in the C cells of the thyroid gland. MCT can quickly spread to the lymph nodes, liver, and lungs. Most cases of MCT are sporadic. However, isolated familial medullary thyroid carcinoma (FMTC) is a type of thyroid cancer that is inherited and can occur in each generation of a family. MCT does not respond to radioactive iodine treatments and tends to have a poor prognosis.
Anaplastic carcinoma is also called undifferentiated thyroid cancer, giant cell cancer, and spindle cell cancer. It is rare. Anaplastic carcinoma is an aggressive cancer. It can spread very quickly to nearby throat and neck structures. Anaplastic carcinoma does not respond to radioactive iodine treatments. It is the most deadly form of thyroid cancer.
A biopsy involves removing a sample of cells and fluid to be examined for cancer. Your doctor will perform a fine needle aspiration. After numbing your skin, your doctor will place a thin needle in the nodule and withdraw fluid and cells. This takes about 10 seconds. The procedure may be repeated a few times to take samples from different areas of the tumor.
Computed tomography (CT) scans and positron emission tomography (PET) scans are used to determine if cancer has spread. Magnetic resonance imaging (MRI) scans provide a very detailed picture of thyroid cancer. In some cases, it may identify if a tumor is cancerous or not. MRIs are also used to see if the cancer has spread to other structures in the body. CT, PET, and MRI scans are painless procedures and they require that you remain motionless while the images are taken.
The experience of thyroid cancer and cancer treatments can be an emotional process for people with cancer and their loved ones. It is important that you receive support from a positive source. Some people find comfort in their family, friends, counselors, co-workers, and faith. Cancer support groups are another good option. They can be a source of information and support from people who understand what you are experiencing. Ask your doctor for cancer support group locations in your area.
PreventionBecause the exact cause of most thyroid cancers is unknown, it is not possible to reliably prevent thyroid cancer at this time. If you have a family history of thyroid cancer, you should ask your doctor about genetic blood testing. Many cases of thyroid cancer can be prevented early. Know the symptoms of thyroid cancer and contact your doctor if you have concerns. Make sure that your doctor checks your thyroid during your routine physical exams.
Am I at Risk
Most people that develop thyroid cancer have no apparent risk factors. However, researchers have identified risk factors that may increase the likelihood of developing thyroid cancer. People with all of the risk factors may never develop the condition; however, the chance of developing thyroid cancer increases with the more risk factors you have. You should tell your doctor about your risk factors and discuss your concerns.
Risk factors for thyroid cancer:
_____ Thyroid cancer is three times more common in women than in men.
_____ Most cases of thyroid cancer occur in people between the ages of 20 and 60.
_____ Follicular thyroid cancer is more common in people with a low-iodine diet. Papillary thyroid cancer is more common in people with a low-iodine diet that have been exposed to radioactivity. In the United States, people consume iodine in salt and foods so this is not as great of a risk factor as it may be for people living in other parts of the world.
_____ During the 1950s, radiation treatments were used to treat acne, fungus infections of the scalp, and enlarged glands or tonsils. Adults that received head and neck radiation treatments in childhood have an increased risk for developing papillary thyroid cancer.
_____ Children that receive low dose radiation treatments for non-Hodgkin’s lymphoma have an increased risk of developing thyroid cancer.
_____ People that have been exposed to radioactive fallout from nuclear reactive material, nuclear weapons testing, or power plant accidents have an increased risk for developing thyroid cancer.
_____ An inherited abnormal gene causes some medullary thyroid cancers. If familial medullary thyroid carcinoma (FMTC) runs in your family, ask your doctor to get tested.
_____ Gardner syndrome, familial polyposis, and Cowden disease are inherited genetic conditions that are associated with higher rates of thyroid cancer.
_____ Certain families appear to have an excess number of papillary thyroid cancers. Researchers have not identified the genetic link as of yet. However, you should let your doctor know if your relatives have thyroid cancer.
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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.
The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.