Thyroid Cancer

The type of thyroid cancer depends on the kind of cells in which cancer starts. Thyroid tissue is made up of two main cell types:

• Follicular cells – these cells produce thyroid hormone. Having too much thyroid hormone (hyperthyroidism) can cause irregular heartbeat, sleep problems, nervousness and other issues. Having too little (hypothyroidism) can cause fatigue and weight gain.
• Parafollicular cells (also called C cells) – these cells produce calcitonin, a hormone that controls the amount of calcium in the blood.

Less common types of thyroid cells include immune system cells (lymphocytes) and supportive (stromal) cells.
 

Thyroid cancer has three major types – differentiated, medullary and anaplastic (undifferentiated).
 

Differentiated Thyroid Cancers

Differentiated thyroid cancers develop from follicular cells. They grow slowly and respond well to treatment. “Differentiated” means the cancer cells look and behave like typical thyroid cells. Some thyroid cancers are called “undifferentiated,” meaning the cells are unlike healthy thyroid cells. Undifferentiated thyroid cancer is faster-growing and more aggressive.

Types of differentiated thyroid cancers include:

• Papillary thyroid cancer – This is the most common thyroid cancer, representing about 80% of all cases. Papillary thyroid cancer is slow-growing and usually develops on one side (lobe) of the thyroid gland. Even when it spreads to lymph nodes in the neck, it’s highly treatable.
• Follicular thyroid cancer – This is the second-most common type, representing about 10-15% of all cases. Follicular thyroid cancer doesn’t usually spread to the lymph nodes, but it can affect other areas of the body, such as the lungs and bones. When detected early, follicular thyroid cancer is very treatable.
• Hürthle cell thyroid cancer – Only about 3% of thyroid cancers are Hürthle-cell type, a rare and more aggressive form. It develops from follicular cells but is much more likely to spread to the lymph nodes. Hürthle cell thyroid cancer can be harder to detect and treat.
   

Medullary Thyroid Cancer (MTC)

About 4% of thyroid cancers are MTC, which develops from parafollicular cells (C cells) located on the inside of the thyroid (medulla). MTC often spreads to the lymph nodes and other body areas ― sometimes even before thyroid nodules appear.

About 20% of MTC cases are familial, meaning they’re caused by inheriting an abnormal gene. Familial MTC often develops in childhood or early adulthood. About 80% of MTC cases aren’t inherited and are called sporadic MTC. This type of thyroid cancer often affects only one side (lobe) of the gland and mainly occurs in older adults.
 

Anaplastic (Undifferentiated) Thyroid Cancer

Anaplastic thyroid cancer is a fast-growing and aggressive cancer that makes up about 2% of all cases. It’s the most undifferentiated thyroid cancer, meaning its cells look very different from normal thyroid cells.

Anaplastic thyroid cancer can quickly spread to other parts of the body. Experts don’t know what causes it, but they believe anaplastic thyroid cancer may develop from other existing thyroid cancers.

Some thyroid cancers are linked to inherited conditions, but most are of unknown cause. Risk factors for thyroid cancer include:

Gender

Women are three times more likely to develop thyroid cancer than men. Some experts believe this could be hormone-related. And about 80% of women develop nodules (lumps or unusual growths) on their thyroid glands.

Radiation Exposure

Medical or environmental radiation exposure can raise your risk of developing thyroid cancer, especially when the exposure occurs in childhood. Radiation sources may include medical treatments or fallout from nuclear accidents or weapons. Risk increases with larger exposures (or doses) of radiation at a young age.

Family History

If you have a parent, sibling or child who had any type of thyroid disease, it increases your risk of developing thyroid cancer.

Inherited Disorders

If you inherit the gene mutation for familial medullary thyroid cancer, you’re more likely to develop the condition. Genetic testing can detect the mutation, and removing the thyroid gland is a preventive measure.

Iodine Deficiency

Countries with low-iodine diets have higher rates of follicular thyroid cancers. But diets high in iodine increase the risk of papillary thyroid cancer. Most Americans get enough iodine in their diets since it’s added to salt.

Having these symptoms may not mean you have thyroid cancer. Still, see your doctor to confirm the cause and get the care you need. Symptoms of thyroid cancer may include:

• A lump or swelling on the thyroid (thyroid nodule)
• Pain at the front of the neck
• Voice changes
• Swallowing difficulty or pain
• Trouble breathing due to a restricted airway
• Constant cough

Mercy uses multiple diagnostic tools to help detect thyroid cancer. If you have symptoms or an issue is found during a medical exam, recommended testing may include:

Laboratory Testing

Blood tests alone don’t diagnose thyroid cancer, but they can help your Mercy doctor find out how your thyroid gland is functioning. Abnormal hormone levels can be a sign of thyroid problems. Additionally, blood tests are also used to monitor certain cancers.

Thyroid Biopsy

The acutal diagnosis of thyroid cancer is made with a biopsy. During a biopsy, your Mercy doctor removes a small sample of thyroid tissue so it can be checked for cancer cells in a lab. If your doctor thinks you need a biopsy, it's generally performed with a fine needle aspiration (FNA) of the thyroid nodule.

Diagnostic Imaging

Diagnostic imaging tests for thyroid cancer may include ultrasounds, CT scans, MRIs and nuclear imaging tests with radioactive iodine.

Radioiodine Scan

The thyroid gland absorbs the body’s iodine, and thyroid cancer cells absorb more of it than surrounding tissues. During a radioiodine scan, a low dose of radioactive iodine is swallowed in pill form or injected into the veins so your Mercy doctor can see where and how iodine is absorbed.

Laryngoscopy (Vocal Cord Exam)

Since thyroid tumors can affect your vocal cords, your Mercy doctor may perform a laryngoscopy to check vocal cord function. A lighted mirror or a laryngoscope (thin, lighted tube) is used to look down your throat at the larynx (voice box).

The most common treatment is surgery to remove all or part of the thyroid gland. Surgical options for thyroid cancer include:

• Lobectomy – the part of the thyroid where cancer is found is removed.
• Near-total thyroidectomy – most of the thyroid gland is removed.
• Total thyroidectomy – the entire thyroid gland is removed.
• Lymphadenectomy – lymph nodes in the neck are removed.

When most or all of your thyroid gland is removed, you’ll usually need to take daily thyroid hormone replacement medication.

Radiation therapy may be used in treating thyroid cancer either after surgery or alone to destroy cancer cells without harming surrounding healthy tissue.

Radioactive iodine (RAI) therapy

Also known as radioiodine therapy, this treatment uses iodine to destroy thyroid tissues not removed during surgery and treats cancer in the lymph nodes or other areas. The thyroid is the only body part that absorbs iodine, so cancer cells can be destroyed without harming your health.

External beam radiation therapy

For medullary and anaplastic thyroid cancers, external beam radiation therapy (radiation delivered by a machine outside the body) may be needed. External beam radiation therapy is most often used for thyroid cancers that have spread beyond the thyroid and don't take up idodine. Two types of external beam radiation therapy used to treat thyroid cancer are IMRT and TomoTherapy.

• Intensity-modulated radiation therapy (IMRT) - IMRT varies the intensity of radiation beams so that stronger doses reach specific thyroid tumor areas.
• TomoTherapy - TomoTherapy delivers radiation on a machine that rotates around the body in an arc, using built-in imaging to target thyroid tumors from many angles.

Thyroid hormone medications can be used to prevent further growth of thyroid tissue. This is sometimes called “suppression therapy.” For people with thyroid cancer, suppression therapy can help prevent it from progressing or coming back.

Chemotherapy (chemo) uses drugs to stop or slow the growth of thyroid cancer cells. Chemo treatment can be delivered orally or directly into the veins by IV. Mercy’s outpatient infusion centers provide a warm and comforting environment for receiving infusion therapy. Patients have the flexibility to receive chemo where it’s most convenient while keeping their electronic medical records centralized.

As side effects to chemo arise, Mercy offers complementary treatments and therapies to reduce and manage side effects.

Targeted therapy uses drugs that aim for specific components inside thyroid cancer cells (targets) that help them grow and spread. This means they destroy cancer cells while leaving your healthy cells intact.