Thyroid Cancer
 |
Thyroid Cancer Symptoms and Warning Signs
Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Dennis Lee, MD
 Each year, about 20,000 people in the U.S. develop cancer of the thyroid gland, a butterfly-shaped organ located on the lower front
of the neck just
below the Adam’s apple. The thyroid gland produces thyroid hormones that
regulate metabolism. Thyroid cancer can occur in anyone, but certain groups of
people are at greater risk for developing the condition. These include:
- Older people – Thyroid
cancer is more common in people over 30 years of age than in younger adults or
children.
- Women are two to three
times more likely than men to develop thyroid cancer.
- Caucasians in the U.S.
are at greater risk than African Americans for development of thyroid cancer.
- Exposure to radiation,
including radiation therapy or nuclear fallout, poses an increased risk for
developing thyroid cancer.
- People with a family history of thyroid cancer or who have rare
syndromes involving tumors of multiple glands are at a greater risk for
thyroid cancers.
There are different types of thyroid cancer (carcinoma
of the thyroid), and the most common types (papillary carcinoma and follicular
carcinoma) are highly curable if detected early. Up to 97% of these common types
of thyroid cancer that occur in younger people are completely cured with
appropriate treatment. Less common types, including medullary carcinoma and
anaplastic carcinoma, tend to spread more rapidly and extensively than the other
types and have a worse prognosis.
|
 |
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.
Next: What causes thyroid cancer, and what are risk factors for thyroid cancer? »
Specialty RSS
