Cancer of the thyroid is a disease in which cancer (malignant) cells are found in the tissues of the thyroid gland. It is more common in women than in men. Most patients are between 25 and 65 years old.

There are four main types of cancer of the thyroid (based on how the
cancer cells look under a microscope): papillary, follicular, medullary, and anaplastic. The chance of recovery (prognosis) depends on the type of thyroid cancer, whether it is just in the thyroid or has spread to other parts of the body (stage), and the patient's age and overall health.

Some types of thyroid cancer grow much faster than others.


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.

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.

Risk Factors

No one knows the exact causes of thyroid cancer. Doctors can seldom explain why one person gets this disease and another does not. However, it is clear that thyroid cancer is not contagious. No one can "catch" cancer from another person.

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. Medullary thyroid cancer can be caused by a change, or alteration, in a gene called RET. The altered RET gene can be passed from parent to child. Nearly everyone with the altered RET gene will develop medullary thyroid cancer.
Being female. Women are two to three times more likely than men to develop thyroid cancer.

Age. Most patients with thyroid cancer are more than 40 years old.
People with anaplastic thyroid cancer are usually more than 65 years old. Race. White people are more likely than Africans to be diagnosed with thyroid cancer.
Not enough iodine in the diet. The thyroid needs iodine to make thyroid hormone. Iodine is always added to salt to protect people from thyroid problems. Thyroid cancer seems to be less common in countries where iodine is part of the diet than in those where not.
Most people who have known risk factors do not get thyroid cancer. On the other hand, many who do get the disease have none of these risk factors.

People who think they may be at risk for thyroid cancer should discuss
this concern with their doctor.

Recognizing Symptoms

Early thyroid cancer often does not cause symptoms. But as the cancer grows, symptoms may include:

A lump, or nodule, in the front of the neck near the Adam's apple;
Hoarseness or difficulty speaking in a normal voice;
Swollen lymph nodes, especially in the neck;
Difficulty swallowing or breathing; or
Pain in the throat or neck.

These symptoms are not sure signs of thyroid cancer. An infection, a
benign goiter, or another problem also could cause these symptoms. Anyone with these symptoms should see a doctor as soon as possible. Only a doctor can diagnose and treat the problem.

Diagnosing

If a person has symptoms that suggest thyroid cancer, the doctor may perform a physical exam and ask about the patient's personal and family medical history. The doctor also may order laboratory tests and imaging tests to produce pictures of the thyroid and other areas.

The exams and tests may include the following:

Physical exam -- The doctor will feel the neck, thyroid, voice box, and lymph nodes in the neck for unusual growths (nodules) or swelling.

Blood tests -- The doctor may test for abnormal levels (too low or too high) of thyroid-stimulating hormone (TSH) in the blood. TSH is made by the pituitary gland in the brain. It stimulates the release of thyroid hormone.
TSH also controls how fast thyroid follicular cells grow.

If medullary thyroid cancer is suspected, the doctor may check for abnormally high levels of calcium in the blood. The doctor also may order blood tests to detect an altered RET gene or to look for a high level of calcitonin.

Ultrasonography -- The ultrasound device uses sound waves that people cannot hear. The waves bounce off the thyroid, and a computer uses the echoes to create a picture called a sonogram. From the picture, the doctor can see how many nodules are present, how big they are, and whether they are solid or filled with fluid.

Radionuclide scanning -- The doctor may order a nuclear medicine scan that uses a very small amount of radioactive material to make thyroid nodules show up on a picture. Nodules that absorb less radioactive material than the surrounding thyroid tissue are called cold nodules. Cold nodules may be benign or malignant. Hot nodules take up more radioactive material than surrounding thyroid tissue and are usually benign.

Biopsy -- The removal of tissue to look for cancer cells is called a biopsy. A biopsy can show cancer, tissue changes that may lead to cancer, and other conditions. A biopsy is the only sure way to know whether a nodule is cancerous.

The doctor may remove tissue through a needle or during surgery:

Fine-needle aspiration: For most patients, the doctor removes a sample of tissue from a thyroid nodule with a thin needle. A pathologist looks at the cells under a microscope to check for cancer. Sometimes, the doctor uses an ultrasound device to guide the needle through the nodule.

Surgical biopsy: If a diagnosis cannot be made from the fine-needle
aspiration, the doctor may operate to remove the nodule. A pathologist then checks the tissue for cancer cells.

Staging

If the diagnosis is thyroid cancer, the doctor needs to know the stage, or extent, of the disease to plan the best treatment. Staging is a careful attempt to learn whether the cancer has spread and, if so, to what parts of the body.

The doctor may use ultrasonography, magnetic resonance imaging (MRI), or computed tomography (CT) to find out whether the cancer has spread to the lymph nodes or other areas within the neck. The doctor may use a nuclear medicine scan of the entire body, such as a radionuclide scan known as the "diagnostic I-131 whole body scan," or other imaging tests to learn whether thyroid cancer has spread to distant sites.

Orthodox Treatment 

People with thyroid cancer have many treatment options. Depending on the type and stage, thyroid cancer may be treated with surgery, radioactive iodine, hormone treatment, external radiation, or chemotherapy. Some patients receive a combination of treatments.

Surgery is the most common treatment for thyroid cancer. The surgeon may remove all or part of the thyroid. The type of surgery depends on the type and stage of thyroid cancer, the size of the nodule, and the patient's age.

Total thyroidectomy -- Surgery to remove the entire thyroid is called a total thyroidectomy. The surgeon removes the thyroid through an incision in the neck. Nearby lymph nodes are sometimes removed, too. If the pathologist finds cancer cells in the lymph nodes, it means that the disease could spread to other parts of the body. In a small number of cases, the surgeon removes other tissues in the neck that have been affected by the cancer.
Some patients who have a total thyroidectomy also receive radioactive iodine or external radiation therapy.

Lobectomy -- Some patients with papillary or follicular thyroid cancer
may be treated with lobectomy. The lobe with the cancerous nodule is removed.
The surgeon also may remove part of the remaining thyroid tissue or nearby lymph nodes. Some patients who have a lobectomy receive radioactive iodine therapy or additional surgery to remove remaining thyroid tissue.

Nearly all patients who have part or all of the thyroid removed will take thyroid hormone pills to replace the natural hormone.

After the initial surgery, the doctor may need to operate on the neck again for thyroid cancer that has spread. Patients who have this surgery also may receive I-131 therapy or external radiation therapy to treat thyroid cancer that has spread.

Radioactive iodine therapy (also called radioiodine therapy) uses radioactive iodine (I-131) to destroy thyroid cancer cells anywhere in
the body. The therapy usually is given by mouth (liquid or capsules) in a small dose that causes no problems for people who are allergic to iodine. The intestine absorbs the I-131, which flows through the bloodstream and collects in thyroid cells. Thyroid cancer cells remaining in the neck and those that have spread to other parts of the body are killed when they absorb I-131.
If the dose of I-131 is low enough, the patient usually receives I-131 as an outpatient. If the dose is high, the doctor may protect others from radiation exposure by isolating the patient in the hospital during the treatment. Most radiation is gone in a few days. Within 3 weeks, only traces of radioactive iodine remain in the body.

Patients with medullary thyroid cancer or anaplastic thyroid cancer generally do not receive I-131 treatment. These types of thyroid cancer rarely respond to I-131 therapy.

Hormone treatment after surgery is usually part of the treatment plan
for papillary and follicular cancer. When a patient takes thyroid hormone pills, the growth of any remaining thyroid cancer cells slows down, which lowers the chance that the disease will return.

After surgery or I-131 therapy (which removes or destroys thyroid tissue), people with thyroid cancer may need to take thyroid hormone pills to replace the natural thyroid hormone.

External radiation therapy (also called radiotherapy) uses high-energy
rays to kill cancer cells. A large machine directs radiation at the neck or at parts of the body where the cancer has spread.
External radiation therapy is local therapy. It affects cancer cells only
in the treated area. External radiation therapy is used mainly to treat
people with advanced thyroid cancer that does not respond to radioactive iodine therapy. For external radiation therapy, patients go to the hospital or clinic, usually 5 days a week for several weeks. External radiation may also be used to relieve pain or other problems.

Chemotherapy, the use of drugs to kill cancer cells, is sometimes used
to treat thyroid cancer. Chemotherapy is known as systemic therapy because the drugs enter the bloodstream and travel throughout the body. For some patients, chemotherapy may be combined with external radiation therapy.

Side Effects of Orthodox Treatment

Because cancer treatment may damage healthy cells and tissues, unwanted side effects sometimes occur. These side effects depend on many factors, including the type and extent of the treatment. Side effects may not be the same for each person, and they may even change from one treatment session to the next. Before treatment starts, the health care team will explain possible side effects and suggest ways to help the patient manage them.

Surgery

Patients are often uncomfortable for the first few days after surgery.
However, medicine can usually control their pain. Patients should feel
free to discuss pain relief with the doctor or nurse. It is also common for patients to feel tired or weak. The length of time it takes to recover from an operation varies for each patient.

After surgery to remove the thyroid and nearby tissues or organs, such as the parathyroid glands, patients may need to take medicine (thyroid hormone) or vitamin and mineral supplements (vitamin D and calcium) to replace the lost functions of these organs. In a few cases, certain nerves or muscles may be damaged or removed during surgery. If this happens, the patient may have voice problems or one shoulder may be lower than the other.

Radioactive Iodine (I-131) Therapy

Some patients have nausea and vomiting on the first day of I-131 therapy. Thyroid tissue remaining in the neck after surgery may become swollen and painful. If the thyroid cancer has spread to other parts of the body, the I-131 that collects there may cause pain and swelling.

Patients also may have a dry mouth or lose their sense of taste or smell for a short time after I-131 therapy. Chewing sugar-free gum or sucking on sugar-free hard candy may help.

During treatment, patients are encouraged to drink lots of water and other fluids. Because fluids help I-131 pass out of the body more quickly, the bladder's exposure to I-131 is reduced.

Because radioactive iodine therapy destroys the cells that make thyroid hormone, patients may need to take thyroid hormone pills to replace the natural hormone.

A rare side effect in men who received large doses of I-131 is loss of
fertility. In women, I-131 may not cause loss of fertility, but some doctors suggest that women avoid pregnancy for one year after I-131
therapy.

Researchers have reported that a very small number of patients may develop leukemia years after treatment with high doses of I-131.

Hormone Treatment

Thyroid hormone pills seldom cause side effects. However, a few patients may get a rash or lose some of their hair during the first months of treatment.

The doctor will closely monitor the level of thyroid hormone in the blood during follow up visits. Too much thyroid hormone may cause patients to lose weight and to feel hot and sweaty. It also may cause chest pain, cramps, and diarrhea. (The doctor may call this condition "hyperthyroidism.") If the thyroid hormone level is too low, the patient may gain weight, feel cold, and have dry skin and hair. (The doctor may call this condition "hypothyroidism.") If necessary, the doctor will
adjust the dose so that the patient takes the right amount.

External Radiation Therapy

External radiation therapy may cause patients to become very tired as
treatment continues. Resting is important, but doctors usually advise patients to try to stay as active as they can. In addition, when patients receive external radiation therapy, it is common for their skin to become red, dry, and tender in the treated area. When the neck is treated with external radiation therapy, patients may feel hoarse or have trouble swallowing. Other side effects depend on the area of the body that is treated. If chemotherapy is given at the same time, the side effects may worsen. The doctor can suggest ways to ease these problems.

Chemotherapy

The side effects of chemotherapy depend mainly on the specific drugs
that are used. The most common side effects include nausea and vomiting, mouth sores, loss of appetite, and hair loss. Some side effects may be relieved with medicine.