Thyroid Cancer Causes,Types, Symptoms, Diagnosis, Treatment, Prevention

Thyroid Cancer Causes,Types, Symptoms, Diagnosis, Treatment, Prevention

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 thyroid cancer?

Thyroid cancer is a disease that you get when abnormal cells begin to grow in your thyroid gland camera. The thyroid gland is shaped like a butterfly and is located in the front of your neck. It makes hormones that regulate the way your body uses energy and that help your body work normally.

Thyroid Cancer Causes,Types, Symptoms, Diagnosis, Treatment, Prevention
Thyroid Cancer

Thyroid cancer is an uncommon type of cancer. Most people who have it do very well, because the cancer is usually found early and the treatments work well. After it is treated, thyroid cancer may come back, sometimes many years after treatment.

Types of thyroid cancer

The thyroid gland contains two types of cells: follicular cells and C cells.  Follicular cells are responsible for the production of thyroid hormone. C cells make calcitonin, a hormone that participates in calcium metabolism. There are four main types of thyroid cancer:

Papillary thyroid cancer

Papillary thyroid cancer develops from the follicular cells and grows slowly. It is the most common type of thyroid cancer. It is usually found in one lobe; only 10% to 20% of papillary thyroid cancers appear in both lobes. Papillary thyroid cancer is a differentiated thyroid cancer, meaning that the tumor looks similar to normal thyroid tissue under a microscope.

Follicular thyroid cancer

Follicular thyroid cancer also develops from the follicular cells and usually grows slowly. Follicular thyroid cancer is also a differentiated thyroid cancer, but it is less common than papillary thyroid cancer.

These two types of cancer are very often curable, especially when found early and in people younger than 45. Together, papillary and follicular thyroid cancers make up about 90% of thyroid cancers.

Medullary thyroid cancer (MTC)

MTC develops in the C cells and is sometimes the result of a genetic syndrome called multiple endocrine neoplasia type 2 (MEN2). This tumor has very little, if any, similarity to normal thyroid tissue. MTC can often be controlled if it is diagnosed and treated before it spreads to other parts of the body. MTC accounts for about 5% of thyroid cancers.

Anaplastic thyroid cancer

This type is rare, accounting for about 2% of thyroid cancers. It is a fast-growing, poorly differentiated thyroid cancer that starts from differentiated thyroid cancer or a benign tumor of the gland. Anaplastic thyroid cancer can be subtyped into giant cell classifications. Because this type of cancer grows so quickly, it is more difficult to treat successfully.

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.

Thyroid Cancer: Causes and  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:


People exposed to high levels of radiation are much more likely than others to develop papillary or follicular thyroid cancer.

One important source of radiation exposure is treatment with x-rays. Between the 1920s and the 1950s, doctors used high-dose x-rays to treat children who had enlarged tonsils, acne, and other problems affecting the head and neck. Later, scientists found that some people who had received this kind of treatment developed thyroid cancer. (Routine diagnostic x-rays -- such as dental x-rays or chest x-rays -- use very small doses of radiation. Their benefits nearly always outweigh their risks. However, repeated exposure could be harmful, so it is a good idea for people to talk with their dentist and doctor about the need for each x-ray and to ask about the use of shields to protect other parts of the body.)

Another source of radiation is radioactive fallout. This includes fallout from atomic weapons testing (such as the testing in the United States and elsewhere in the world, mainly in the 1950s and 1960s), nuclear power plant accidents (such as the Chornobyl [also called Chernobyl] accident in 1986), and releases from atomic weapons production plants (such as the Hanford facility in Washington state in the late 1940s). Such radioactive fallout contains radioactive iodine (I-131). People who were exposed to one or more sources of I-131, especially if they were children at the time of their exposure, may have an increased risk for thyroid diseases.

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. A blood test can detect an altered RET gene. If the abnormal gene is found in a person with medullary thyroid cancer, the doctor may suggest that family members be tested. For those found to carry the altered RET gene, the doctor may recommend frequent lab tests or surgery to remove the thyroid before cancer develops. When medullary thyroid cancer runs in a family, the doctor may call this "familial medullary thyroid cancer" or "multiple endocrine neoplasia (MEN) syndrome." People with the MEN syndrome tend to develop certain other types of cancer.

A small number of people with a family history of goiter or certain precancerous polyps in the colon are at risk for developing papillary thyroid cancer.

Being female

In the United States, women are two to three times more likely than men to develop thyroid cancer.


Most patients with thyroid cancer are more than 40 years old. People with anaplastic thyroid cancer are usually more than 65 years old.


In the United States, white people are more likely than African Americans to be diagnosed with thyroid cancer.

Not enough iodine in the diet

The thyroid needs iodine to make thyroid hormone. In the United States, iodine is added to salt to protect people from thyroid problems. Thyroid cancer seems to be less common in the United States than in countries where iodine is not part of the diet.

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. The doctor may suggest ways to reduce the risk and can plan an appropriate schedule for checkups.

Thyroid Cancer 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.

Diagnosis of Thyroid Cancer

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.


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.


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.

When to see a doctor 

If you experience any these signs or symptoms, make an appointment with your doctor. Thyroid cancer isn't common, so your doctor may investigate other causes of your signs and symptoms first.

How is staging determined for thyroid cancer?

If the biopsy shows that you have cancer, your doctor will need to learn the extent (stage) of the disease to help you choose the best treatment.

The stage is based on the size of the nodule and whether the cancer has invaded nearby tissues or spread to other parts of the body. Thyroid cancer spreads most often to nearby tissues in the neck or to lymph nodes. It may also spread to the lungs and bones.

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

Staging may involve one or more of these tests:

  • Ultrasound: An ultrasound exam of your neck may show whether cancer has spread to lymph nodes or other tissues near your thyroid.
  • CT scan: An x-ray machine linked to a computer takes a series of detailed pictures of your neck and chest area. A CT scan may show whether cancer has spread to lymph nodes, other areas in your neck, or your chest.
  • MRI: MRI uses a powerful magnet linked to a computer. It makes detailed pictures of your neck and chest area. MRI may show whether cancer has spread to lymph nodes or other areas.
  • Chest x-ray: An x-ray of the chest can often show whether cancer has spread to the lungs.
  • Whole body scan: You may have a whole body scan to see if cancer has spread from the thyroid to other parts of the body. You get a small amount of a radioactive substance (such as radioactive iodine). The substance travels through the bloodstream. Thyroid cancer cells in other organs or the bones take up the substance. Thyroid cancer that has spread may show up on a whole body scan.

Preparing for Treatment for Thyroid Cancer

The doctor can describe treatment choices and discuss the results expected with each treatment option. The doctor and patient can work together to develop a treatment plan that fits the patient's needs.

Treatment depends on a number of factors, including the type of thyroid cancer, the size of the nodule, the patient's age, and whether the cancer has spread.

These are some questions a person may want to ask the doctor before treatment begins:

  • What type of thyroid cancer do I have?
  • Has the cancer spread? What is the stage of the disease?
  • Do I need any more tests to check for spread of the disease?
  • What are my treatment choices? Which do you recommend for me? Why?
  • What are the benefits of each kind of treatment?
  • What are the risks and possible side effects of each treatment?
  • What is the treatment likely to cost?
  • How will the treatment affect my normal activities?
  • Would a clinical trial (research study) be appropriate for me? Can you help me find one?

People do not need to ask all of their questions or understand all of the answers at one time. They will have other chances to ask the doctor to explain things that are not clear and to ask for more information.

What are the treatment options for thyroid cancer?

Treatment options which may be considered include surgery, radioactive iodine and radiotherapy. More than one type of treatment may be given. Most types of thyroid cancer can usually be treated successfully and many people with thyroid cancer are cured.

You should have a full discussion with a specialist who knows your case. They will be able to give the pros and cons, likely success rate, possible side-effects, and other details about the various possible treatment options for your type of cancer.

You should also discuss with your specialist the aims of treatment. For example:

  • In some cases, the treatment aims to cure the cancer. Some thyroid cancers can be cured, particularly if they are treated in the early stages of the disease. (Doctors tend to use the word remission rather than the word cured. Remission means there is no evidence of cancer following treatment. If you are in remission, you may be cured. However, in some cases a cancer returns months or years later. This is why doctors are sometimes reluctant to use the word cured.)
  • In some cases, the treatment aims to control the cancer. If a cure is not realistic, with treatment it is often possible to limit the growth or spread of the cancer so that it progresses less rapidly. This may keep you free of symptoms for some time.
  • In some cases, treatment aims to ease symptoms. For example, if a cancer is advanced then you may require treatments such as painkillers or other treatments to help to keep you free of pain or other symptoms. Some treatments may be used to reduce the size of a cancer, which may ease symptoms such as pain.


An operation to remove all (or sometimes part) of the thyroid gland is the most common treatment. Sometimes the surgeon also removes some, or all, of the lymph nodes close to the thyroid gland, to see whether the cancer has spread into them. This can help to reduce the risk of the cancer coming back after surgery.

If the cancer is at an early stage and not spread then surgery alone may be curative.

After your operation, it is likely you will need to take thyroid hormones to replace those normally produced by the thyroid gland.

Radioactive iodine treatment

Many people are given radioactive iodine treatment after their thyroid surgery. Radioactive iodine treatment uses radioactive iodine (I-131) to destroy thyroid cancer cells anywhere in the body. This treatment is usually given as liquid or capsules. The thyroid cancer cells absorb the iodine and receive a very high dose of radiation, which will help to destroy them. As other cells in the body do not absorb iodine, they are not affected by the radioactive iodine. Most radiation is gone from your body in a few days.

If you have medullary thyroid cancer or anaplastic thyroid cancer then it is unlikely you will receive radioactive iodine treatment, as these types of thyroid cancer rarely respond to it.

Hormone treatment

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.


Radiotherapy is a treatment which uses high-energy beams of radiation which are focused on cancerous tissue. This kills cancer cells, or stops cancer cells from multiplying. Radiotherapy may be advised if you have thyroid cancer that does not respond to radioactive iodine treatment.


Chemotherapy is a treatment of cancer by using anti-cancer medicines which kill cancer cells, or stop them from multiplying. Chemotherapy is rarely used to treat cancer of the thyroid but may be used if the cancer returns or has spread to other parts of the body.

Followup Care

Followup care after treatment for thyroid cancer is an important part of the overall treatment plan. Regular checkups ensure that any changes in health are noted. Problems can be found and treated as soon as possible. Checkups may include a careful physical exam, x-rays and other imaging tests (such as a nuclear medicine scan), and laboratory tests (such as a blood test for calcitonin). The doctor can explain the followup plan -- how often the patient must visit the doctor and which types of tests are needed.

An important test after thyroid cancer treatment measures the level of thyroglobulin in the blood. Thyroid hormone is stored in the thyroid as thyroglobulin. If the thyroid has been removed, there should be very little or no thyroglobulin in the blood. A high level of thyroglobulin may mean that thyroid cancer cells have returned.

For six weeks before the thyroglobulin test, patients must stop taking their usual thyroid hormone pill. For part of this time, some patients may take a different, shorter-lasting thyroid hormone pill. But all patients must stop taking any type of thyroid hormone pill for the last two weeks right before the test. Without adequate levels of thyroid hormone, patients are likely to feel uncomfortable. They may gain weight and feel very tired. It may be helpful to talk with the doctor or nurse about ways to cope with such problems. After the test, patients go back to their usual treatment with thyroid hormone pills.

The doctor may request an I-131 scan of the entire body. This may be called a "diagnostic I-131 whole body scan." For a short time (usually six weeks) before this scan, the patient stops taking thyroid hormone pills. Thyroid cancer cells anywhere in the body will show up on the scan. After the test, the doctor will tell the patient when to start taking thyroid hormone pills again.

Prevention for Thyroid Cancer

Doctors aren't sure what causes most cases of thyroid cancer, so there's no way to prevent thyroid cancer in people who have an average risk of the disease.

Prevention for people with a high risk 

People with an inherited gene mutation that increases the risk of medullary thyroid cancer may opt to have thyroid surgery to prevent cancer (prophylactic thyroidectomy). Discuss your options with a genetic counselor who can explain your risk of thyroid cancer and your treatment options.

Prevention for people near nuclear power plants 

Fallout from an accident at a nuclear power plant could cause thyroid cancer in people living nearby. If you live within 10 miles of a nuclear power plant in the United States, you may be eligible to receive a medication (potassium iodide) that blocks the effects of radiation on the thyroid. If an emergency were to occur, you and your family could take the potassium iodide tablets to help prevent thyroid cancer. Contact your state or local emergency management department for more information.

Support for People with Thyroid Cancer

Living with a serious disease such as cancer is not easy. Some people find they need help coping with the emotional and practical aspects of their disease. Support groups can help. In these groups, patients or their family members get together to share what they have learned about coping with the disease and the effects of treatment. Patients may want to talk with a member of their health care team about finding a support group. Groups may offer support in person, over the telephone, or on the Internet.

People living with cancer may worry about caring for their families, keeping their jobs, or continuing daily activities. Concerns about treatments and managing side effects, hospital stays, and medical bills are also common. Doctors, nurses, and other members of the health care team can answer questions about treatment, working, or other activities. Meeting with a social worker, counselor, or member of the clergy can be helpful to those who want to talk about their feelings or discuss their concerns. Often, a social worker can suggest resources for financial aid, transportation, home care, or emotional support.

The Cancer Information Service can provide information to help patients and their families locate programs, services, and publications.

Side Effects of Thyroid Cancer Treatments

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.


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 followup 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.


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.