What Are the Symptoms of Medullary Thyroid Cancer?

Medullary thyroid cancer (medullary thyroid carcinoma) is a type of cancer that occurs when C cells of the thyroid gland grow out of control. The C cells make calcitonin, a hormone that helps control calcium levels in blood. Medullary thyroid cancer can also spread (metastasize) to the lymph nodes, lungs, or liver before a thyroid nodule is discovered.

Medullary thyroid cancer is the rarest type of thyroid cancer, accounting for only about 4% of all thyroid cancer cases, and it is more difficult to detect and treat than other types of thyroid cancer. 

There are two types of medullary thyroid cancer (MTC):

• Sporadic medullary thyroid cancer
  • Accounts for about 80% of cases of MTC
  • Is not inherited 
  • Occurs mostly in older adults 
  • Often affects only one thyroid lobe
• Familial medullary thyroid cancer 
  • Inherited  
  • 20% to 25% of MTC can occur in each generation of a family
  • Often develops during childhood or early adulthood and can spread early
  • Usually affects several areas of both lobes
  • Often linked with an increased risk of other types of tumors

Symptoms of medullary thyroid cancer include: 

• A lump or nodule in the thyroid
  • Nodule may cause no symptoms
  • In some cases, the tumor may have spread to lymph nodes in the neck, which may be enlarged 
• Pain in the neck, jaw, or ear
• Difficulty breathing or swallowing if the nodule is large
• Hoarseness if the cancer invades the nerve that controls the vocal cords

About 20% of medullary thyroid cancers are known as familial medullary thyroid carcinoma (FMTC) and result from inheriting an abnormal gene. This type of medullary thyroid cancer often develops during childhood or early adulthood and can spread early.

The other 80% of medullary thyroid cancers are not inherited and the cause is unknown.

Medullary thyroid cancer is diagnosed with a patient history and physical examination. Tests used to help diagnose medullary thyroid cancer include: 

• Imaging tests
  • Ultrasound
  • Computerized tomography (CT) scan
  • Magnetic resonance imaging (MRI) scan
• Fine needle aspiration (FNA) biopsy 
• Blood tests
  • Calcitonin
  • Carcinoembryonic antigen (CEA)

Medullary thyroid cancer is usually treated with removal of the thyroid gland (thyroidectomy). Surgery may also include removal of any affected lymph nodes.

After surgery, patients must take thyroid hormone replacement medication for life.

In people who have a high risk for developing MTC, such as people with certain gene changes, a thyroidectomy may be performed to prevent cancer.

Other treatments for medullary thyroid cancer include: 

• Chemotherapy
  • Vandetanib (Caprelsa)
  • Cabozantinib (Cometriq)
• Targeted therapies 
• Radiation therapy (not commonly used)
  • External beam radiation therapy