Thyroid cancer

Thyroid Cancer at a Glance

• Women are more than three times as likely as men to develop thyroid cancer.
• Other risk factors include radiation exposure, family or personal history of goiters, benign thyroid growths or colon growths, age over 45, lack of iodine in diet.
• Early thyroid cancer often has no symptoms, so it's important if you have risk factors to let your physician know so he or she can check you.
• Other symptoms may include a lump in the front of the neck, hoarseness or voice changes, swollen lymph nodes in the neck, trouble swallowing or breathing, pain in the throat or neck that does not go away.
• There are several successful treatments for thyroid cancer.

The thyroid is a butterfly-shaped gland and lies at the front of the neck, beneath the larynx. It has two parts, or lobes. The two lobes are separated by a thin section called the isthmus.

Thyroid gland has two kinds of cells that make hormones. Follicular cells make thyroid hormone, which affects heart rate, body temperature, and energy level. C cells make calcitonin, a hormone that helps control the calcium level in the blood.

About Thyroid Cancer

All cancers begin in cells, the body's basic unit of life. Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place.

Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.

Cancer that forms in the thyroid gland is referred to as Thyroid cancer. For the year 2006, 5.4 new cases of Thyroid cancer were reportedly diagnosed per 100,000 population (approximately 16,500 new cases in 2006 in United States).

Growths on the thyroid are often called nodules. Thyroid nodules can be benign or malignant. Benign nodules are rarely a threat to life. They don't invade the tissues around them or spread to other parts of the body. Usually, they don't need to be removed.

Malignant nodules may sometimes be a threat to life, can invade and spread to nearby tissues and organs. They often can be removed or destroyed, but sometimes the cancer returns.

Cancer cells can spread by breaking away from the original tumor. They enter blood vessels or lymph vessels, which branch into all the tissues of the body. The cancer cells attach to other organs and grow to form new tumors that may damage those organs. The spread of cancer is called metastasis.

Types of Thyroid Cancer

There are several types of thyroid cancer:

• Papillary thyroid cancer: In the United States, this type makes up about 80 percent of all thyroid cancers. It begins in follicular cells and grows slowly. If diagnosed early, most people with papillary thyroid cancer can be cured.
• Follicular thyroid cancer: This type makes up about 15 percent of all thyroid cancers. It begins in follicular cells and grows slowly. If diagnosed early, most people with follicular thyroid cancer can be treated successfully.
• Medullary thyroid cancer: This type makes up about 3 percent of all thyroid cancers. It begins in the C cells of the thyroid. Cancer that starts in the C cells can make abnormally high levels of calcitonin. Medullary thyroid cancer tends to grow slowly. It can be easier to control if it's found and treated before it spreads to other parts of the body.
• Anaplastic thyroid cancer: This type makes up about 2 percent of all thyroid cancers. It begins in the follicular cells of the thyroid. The cancer cells tend to grow and spread very quickly. Anaplastic thyroid cancer is very hard to control.

Risk Factors

Research has shown that people with certain risk factors are more likely than others to develop thyroid cancer. A risk factor is anything that increases a person's chance of developing a disease. The following risk factors are associated with an increased chance of developing thyroid cancer:

• Radiation: People exposed to high levels of radiation are much more likely than others to develop papillary or follicular thyroid cancer.
• Family history of goiters or colon growths: A small number of people with a family history of having goiters (swollen thyroids) with multiple thyroid nodules are at risk for developing papillary thyroid cancer. Also, a small number of people with a family history of having multiple growths on the inside of the colon or rectum (familial polyposis) are at risk for developing papillary thyroid cancer.
• Personal history: People with a goiter or benign thyroid nodules have an increased risk of thyroid cancer.
• Being female: In the United States, women are almost three times more likely than men to develop thyroid cancer.
• Age over 45: Most people with thyroid cancer are more than 45 years old. Most people with anaplastic thyroid cancer are more than 60 years old.
• Iodine: Iodine is a substance found in shellfish and iodized salt. Scientists are studying iodine as a possible risk factor for thyroid cancer. Too little iodine in the diet may increase the risk of follicular thyroid cancer. However, other studies show that too much iodine in the diet may increase the risk of papillary thyroid cancer. More studies are needed to know whether iodine is a risk factor.

Having one or more risk factors does not mean that a person will get thyroid cancer. Most people who have risk factors never develop cancer.