Is Thyroid Cancer Deadly?

The survival rates for thyroid cancer vary depending on the type and spread of the cancer, as well as how early oncologists start treatment.

Thyroid cancer occurs when cells in the thyroid become abnormal and grow out of control. The thyroid gland is located in the neck and produces thyroid hormone which helps regulate metabolism, heart rate, blood pressure, and body temperature.

There are different types of thyroid cancer. The main types of thyroid cancer are:

• Differentiated 
  • Papillary
    • Accounts for about 80% thyroid cancers 
    • Grows slowly and usually develops in only one lobe of the thyroid gland 
    • Often spreads to the lymph nodes in the neck
    • Rarely fatal
  • Follicular 
    • Accounts for about 10% thyroid cancers
    • More common in countries where people don’t get enough iodine in the diet
    • Does not spread to lymph nodes, but can spread to other parts of the body, such as the lungs or bones
    • The prognosis is very good in most cases
  • Hürthle cell
    • Accounts for about 3% of thyroid cancers 
    • Harder to find and to treat
• Medullary, more difficult to find and treat
  • Sporadic MTC
    • Accounts for about 8 out of 10 cases of MTC
    • Is not inherited (does not run in families)
    • Occurs mostly in older adults and often affects only one thyroid lobe
  • Familial MTC 
    • Inherited and 20% to 25% can occur in each generation of a family
    • Often develops during childhood or early adulthood and can spread early 
    • Cancer usually occurs in several areas of both lobes
• Anaplastic (also called undifferentiated carcinoma) 
  • Rare and aggressive form of thyroid cancer, making up about 2% of all thyroid cancers
  • May develop from an existing papillary or follicular cancer
  • Often spreads quickly into the neck and to other parts of the body, and is very hard to treat
• Less than 4% of cancers found in the thyroid are thyroid lymphomas, thyroid sarcomas, or other rare tumors

Thyroid cancer may not have symptoms early on. When symptoms do occur, they may include:

• Growth (nodule) on the neck that may grow slowly or quickly
• Swelling in the neck
• Pain in the front of the neck, that may go up to the ears
• Hoarseness, voice changes, or being unable to talk
• Difficulty breathing
• Trouble swallowing
• Cough (may include coughing up blood)

The cause of thyroid cancer is unknown but it is linked with a number of genetic (inherited) conditions.

Other risk factors for thyroid cancer include: 

• Being female: thyroid cancers are 3 times common in women than in men
• Age: women are usually in their 40s or 50s when diagnosed and men are usually in their 60s or 70s
• Genetic conditions
  • Familial adenomatous polyposis (FAP)
  • Cowden disease
  • Carney complex, type I
  • Familial nonmedullary thyroid carcinoma
• Family history of thyroid cancer
• Radiation exposure such as from certain medical treatments and radiation fallout from power plant accidents or nuclear weapons
• Being overweight or obese
• Low iodine in the diet (more common in other parts of the world; most people un the U.S. get enough iodine in the diet)

Thyroid cancer is diagnosed with a history and physical exam. If a growth on the thyroid gland is seen or felt, tests may include: 

• Imaging tests 
  • Ultrasound
  • Radioiodine scans
  • Chest X-ray
  • Computed tomography (CT) scan
  • Magnetic resonance imaging (MRI) scan
  • Positron emission tomography (PET) scan
• Fine needle aspiration biopsy
• Blood tests
  • Thyroid-stimulating hormone (TSH)
  • T3 and T4 (thyroid hormones)
  • Thyroglobulin
  • Calcitonin
  • Carcinoembryonic antigen (CEA)
  • Other blood tests such as complete blood count (CBC), tests for bleeding disorders, and tests to check liver and kidney function

Treatment for thyroid cancer usually includes one or more of the following:

• Surgery to remove the cancer
• Radioactive iodine ("radioiodine therapy") 
• Thyroid hormone 
• External-beam radiation therapy 
• Chemotherapy

The American Cancer Society estimates about 2,180 deaths from thyroid cancer (1,040 men and 1,140 women) in 2020. 

Life expectancy for thyroid cancer is often expressed in 5-year survival rates, that is, how many people will be alive 5 years after diagnosis. 

Papillary thyroid cancer 5-year survival rates:

• Localized (no sign the cancer has spread outside the thyroid): near 100%
• Regional (cancer has spread outside the thyroid to nearby structures): 99%
• Distant (cancer has spread to distant parts of the body such as the bones): 78%

Follicular thyroid cancer 5-year survival rates:

• Localized (no sign the cancer has spread outside the thyroid): near 100%
• Regional (cancer has spread outside the thyroid to nearby structures): 96%
• Distant (cancer has spread to distant parts of the body such as the bones): 63%

Medullary thyroid cancer 5-year survival rates:

• Localized (no sign the cancer has spread outside the thyroid): near 100%
• Regional (cancer has spread outside the thyroid to nearby structures): 90%
• Distant (cancer has spread to distant parts of the body such as the bones): 39%

Anaplastic thyroid cancer 5-year survival rates:

• Localized (no sign the cancer has spread outside the thyroid): 31%
• Regional (cancer has spread outside the thyroid to nearby structures): 12%
• Distant (cancer has spread to distant parts of the body such as the bones): 4%