Thyroid cancer

 Thyroid cancer facts

• The thyroid gland produces thyroid hormones which are important in the normal regulation of the metabolism of the body.
• Thyroid cancer is three times more common in women than in men.
• There are four major types of thyroid cancer: papillary, follicular, medullary, and anaplastic.
• The cause of thyroid cancer is unknown, but certain risk factors have been identified and include a family history of goiter, exposure to high levels of radiation, and certain hereditary syndromes.
• The National Cancer Institute recommends that anyone who received radiation to the head or neck in childhood be examined by a doctor every one to two years to detect potential thyroid cancer.
• The most common signs and symptoms of thyroid cancer include a lump, or thyroid nodule, that can be felt in the neck, trouble swallowing, throat or neck pain, swollen lymph nodes in the neck, cough, and vocal changes.
• The only certain way to tell whether a thyroid lump is cancerous is by examining the thyroid tissue obtained using a needle or surgery for biopsy. A CEA blood test, physical exam, X-rays, CT scans, PET scans, ultrasounds, and MRIs may also be used to help establish a definitive diagnosis and determine staging.
• Surgery is the most common form of treatment for thyroid cancer that has not spread to other areas of the body. Radiation therapy, chemotherapy, and radioactive iodine treatment are also treatment options for thyroid cancer.
• The survival rate and prognosis of thyroid cancer depends upon a few factors, including the individual's age, the size of the tumor, and whether the cancer has metastasized.
• It is not possible to prevent most cases of thyroid cancer.

What is the thyroid?

The thyroid is a gland in the neck. It 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 level of calcium in the blood.

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

A healthy thyroid is a little larger than a quarter. It usually cannot be felt through the skin. A swollen lobe might look or feel like a lump in the front of the neck. A swollen thyroid is called a goiter. Most goiters are caused by not enough iodine in the diet. Iodine is a substance found in shellfish and iodized salt.

What is cancer, and what are the types of thyroid cancer?

Cancer is a group of many related diseases. All cancers begin in cells, the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body.

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. Growths on the thyroid are usually called nodules.

Thyroid nodules can be benign or malignant:

• Benign nodules are not cancer. Cells from benign nodules do not spread to other parts of the body. They are usually not a threat to life. Most thyroid nodules (more than 90 percent) are benign.
• Malignant nodules are cancer. They are generally more serious and may sometimes be life threatening. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant nodule and enter the bloodstream or the lymphatic system. That is how cancer spreads from the original cancer (primary tumor) to form new tumors in other organs. The spread of cancer is called metastasis.

The following are the major types of thyroid cancer:

• Papillary and follicular thyroid cancers account for 80 to 90 percent of all thyroid cancers. Both types begin in the follicular cells of the thyroid. Most papillary and follicular thyroid cancers tend to grow slowly. If they are detected early, most can be treated successfully.
• Medullary thyroid cancer accounts for 5 to 10 percent of thyroid cancer cases. It arises in C cells, not follicular cells. Medullary thyroid cancer is easier to control if it is found and treated before it spreads to other parts of the body.
• Anaplastic thyroid cancer is the least common type of thyroid cancer (only 1 to 2 percent of cases). It arises in the follicular cells. The cancer cells are highly abnormal and difficult to recognize. This type of cancer is usually very hard to control because the cancer cells tend to grow and spread very quickly.

If thyroid cancer spreads (metastasizes) outside the thyroid, cancer cells are often found in nearby lymph nodes, nerves, or blood vessels. If the cancer has reached these lymph nodes, cancer cells may have also spread to other lymph nodes or to other organs, such as the lungs or bones.

When cancer spreads from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if thyroid cancer spreads to the lungs, the cancer cells in the lungs are thyroid cancer cells. The disease is metastatic thyroid cancer, not lung cancer. It is treated as thyroid cancer, not as lung cancer. Doctors sometimes call the new tumor "distant" or metastatic disease.