Thyroid Cancer

What is thyroid cancer?

Thyroid cancer is cancer of the thyroid.  Papillary thyroid cancer accounts for 80 to 85 percent of thyroid cancers.  It involves the follicle cells and is typically a slow growing cancer, though it often spreads early to the lymph nodes in the neck.  It is usually found in one of the two thyroid lobes.  Follicular thyroid cancer, accounting for 5 to 10 percent of thyroid cancer, involves the follicle cell.  It typically is slow growing and usually does not spread to the neck lymph nodes.  Anaplastic and medullary are two other thyroid cancers that occur less often.  Anaplastic makes up 1 to 2 percent of thyroid cancer and spreads quickly and is hard to control.  It starts in the follicular cells.  Medullary thyroid cancer is easy to control if found early and starts in the C cells.

What are risk factors for thyroid cancer?

The exact cause of thyroid cancer is not known.  There are several risk factors that increase a person’s chance of getting thyroid cancer.

• Age – Most patients with thyroid cancer are over the age of 40.
• Gender – Women are more likely to get thyroid cancer than men.
• Family history – A person with a genetic mutation in the RET gene will most likely develop medullary thyroid cancer.  A small number of people with a family history of familial polyposis and Gardner’s syndrome have an increased risk of developing thyroid cancer.
• Diet – Papillary and follicular thyroid cancers are found more often in countries where people’s diet are low in iodine.
• Radiation – Exposure to high doses of radiation increases the risk for papillary or follicular thyroid cancer.  In the past, children were sometimes treated with high doses of radiation for conditions of the head and neck, ranging from acne to shrinking the tonsils and adenoids.  Some of these children later developed thyroid cancer.  Exposure to radiation fallout, such as from atomic weapons testing in the 1950’s and 1960’s or nuclear power plant accidents, increases the risk for thyroid cancer.

Most people who get thyroid cancer have no risk factors and most people with risk factors do not get thyroid cancer.

What are prevention strategies for thyroid cancers?

Most cases of thyroid cancer cannot be prevented.  It is important to avoid unnecessary exposure to radiation, especially in young children.  If there is a family history of medullary thyroid cancer, it is important to discuss this with your healthcare provider.  Most hereditary medullary thyroid cancers can be prevented through the removal of the thyroid.

Is screening available?

Routine screening for thyroid cancer is not recommended.  There is no single blood test to check for thyroid cancer.  If you have a family history of medullary thyroid cancer, it is important to discuss this with your healthcare provider.

What are the symptoms of thyroid cancer?

Early thyroid cancer often does not produce symptoms.  Following are possible symptoms of thyroid cancer.

• Swollen lymph nodes, especially in the neck
• Hoarseness or difficulty speaking
• A lump, or nodule in the front of the neck
• Difficulty swallowing or breathing
• Pain in the neck or throat

These symptoms may not indicate thyroid cancer, but could be a result of other conditions.  If you have any of these symptoms, it is important to discuss them with your healthcare provider.

How is thyroid cancer diagnosed?

If thyroid cancer is suspected, your doctor will most likely perform a physical exam, take a medical and family history and order laboratory or imaging tests.  Following are tests and exams that may be used to diagnose thyroid cancer.

• Ultrasound – This is used to show how many nodules are present, the size of the nodules and if they are solid or fluid filled.
• Radionuclide scanning – This is also called a thyroid scan.  Radioactive iodine or technetium is taken orally or injected in the veins.  This material concentrates in the thyroid gland.  Pictures are taken to determine cold nodules, which indicate a nodule that may be benign or cancerous, or hot nodules, which typically indicate benign nodules.
• Fine needle aspiration- A thin needle is placed in the nodule to remove samples of the tissue for a pathologist to exam under a microscope to determine if it is cancer.
• Surgical biopsy – If a diagnosis cannot be made from a fine needle aspiration, a doctor may remove the nodule surgically.  A pathologist will check the tissue for cancer cells.
• Computed Tomography (CT) scans – This is not used to diagnose thyroid cancer, but rather to identify the type of tumor and if it has spread, which will help in staging the cancer.
• Magnetic resonance imaging (MRI) – As with the CT scan, the MRI can be useful in looking at the type of cancer and if it has spread.
  

What is staging?

Staging describes the extent of the cancer.  It determines if the cancer has spread and if so, what parts of the body are affected.  Staging a cancer is important to assist the doctor to determine the appropriate course of treatment and assess an accurate prognosis. 

The most common staging system is the TNM.

• T – size of the tumor
• N – degree to which regional lymph nodes are involved
• M – the absence or presence of distant metastases

Once the TNM has been determined, then a stage of I, II, III or IV is assigned.

• Stage I – cancers are small and local and usually curable
• Stage II & III – typically these are locally advanced and could involve the lymph nodes
• Stage IV – cancer has metastasized and can be inoperable
  

What are treatment options?

There are five main treatments for thyroid cancer.  Determining which treatment or combination of treatments to use depends on factors such as type and stage of the cancer.  Following are the treatments.

• Surgery – This is the most common treatment.  The complete or partial thyroid is removed.
• Radioactive iodine therapy – Radioactive iodine I-131 is administered usually orally in small doses.  The thyroid cancer cells are killed when they absorb the I-131. 
• Hormone treatment – After surgery for papillary and follicular thyroid cancer, hormones are often given to slow the growth of any remaining thyroid cancer cells.  Hormone treatment is also used to replace the natural thyroid hormone, which is destroyed or removed with surgery and radioactive iodine therapy.
• External radiation therapy - This uses high energy rays to kill cancer cells.  It is used mainly to treat advanced thyroid cancer.
• Chemotherapy – This systemic drug is administered through the veins to kill cancer cells.  It is sometimes combined with radiation therapy.
  

What clinical trials are available?

Clinical trials are studies that seek to find better ways to prevent, screen, diagnose and treat a disease such as cancer.  Clinical trials test new approaches to treatment, such as new drugs, new approaches to surgery or radiation therapy, or a combination of treatments.

Learn more about clinical trials.

What questions should I ask my doctor?

It is often helpful to make a list of questions before an appointment.  This will help you to remember what the doctor says.  Patients and care givers can write notes or ask if they may use a tape recorder.  Sometimes it is helpful to have a family member or friend at the appointment to take notes, ask questions or just listen.  Below are a few suggested questions a patient may ask their doctor.

Will you please write down the type of cancer that I have?

What stage is my cancer and what does that mean?

What are my treatment options?

What treatment do you recommend and why?

What are the risks and benefits of each treatment?

What are possible side effects of treatment?

How will you help manage my side effects?

How will treatment affect my normal activities?

Are there specific things I must do to get ready for treatment?

Are there other things I can be doing to help with my treatment, such as diet and exercise?

What resources can I use to learn more about my cancer and help me deal with it?

Make an appointment

Resources

American Cancer Society – www.cancer.org, 1-800-ACS-2345

Cancerpage.com – www.cancerpage.com

CancerSource.com – www.cancersource.com

National Cancer Institute – www.cancer.gov, 1-800-4CANCER