Papillary and follicular thyroid cancers are the most common types of thyroid cancer. They both grow slowly, respond well to treatment, and can often be cured.

Your thyroid gland is a butterfly-shaped gland located across the front of your neck, and its main function is to create hormones that control your metabolism.

According to the Centers for Disease Control and Prevention (CDC), about 33,000 women and 12,000 men in the United States develop thyroid cancer each year. Thyroid cancer is now the ninth most common cancer in the United States.

The four main types of thyroid cancer are:

Papillary and follicular thyroid cancer make up about 95% of thyroid cancers. Both cancers have high response rates to treatment and can often be cured. Doctors can recognize the difference between these two cancers by looking at the cells under a microscope.

This article compares the similarities and differences between these two types of thyroid cancer.

Papillary and follicular thyroid cancer are classified as “differentiated” thyroid cancers, which means that the cancer cells resemble normal cells under a microscope. Differentiated cancers tend to spread slowly.

Follicular and papillary cancers are similar in that they both start in the follicular cells. Follicular cells are the main type of cell in your thyroid and produce and secrete the hormones thyroxine (T4) and triiodothyronine (T3).

Papillary thyroid cancer

Papillary cancer is the most common type of thyroid cancer, and people with this type of cancer have the best outlook. It tends to grow slowly, but some specific subtypes may grow quickly.

Under a microscope, the cancer cells appear:

  • enlarged
  • oval shaped
  • elongated

In most cases, the cancer is confined to one lobe of your thyroid but can spread to the lymph nodes.

Follicular thyroid cancer

Follicular cancer is significantly less common than papillary thyroid cancer, but it’s still the second most common type of thyroid cancer. Follicular cancer is less likely to spread to the lymph nodes, but it can spread to other distant sites in the body such as the bones and lungs.

Follicular thyroid cancer is generally made up of a solitary mass of cells enclosed in thick tissue. The cancer cells may spread to the surrounding tissue or blood vessels. Follicular cancer is usually defined by the takeover of these tissues without the features of papillary thyroid cancer.

Papillary thyroid cancerFollicular thyroid cancer
Prevalenceabout 80%–85% of thyroid cancersabout 10%–15% of thyroid cancers
Type of cells affectedfollicular cellsfollicular cells
Symptoms and characteristics· hoarseness
· shortness of breath
· trouble swallowing
· more likely to spread to lymph nodes
· hoarseness
· shortness of breath
· trouble swallowing
· more likely to spread to distant areas
· less likely to spread to lymph nodes
Unique risk factorshigh iodine intakelow iodine intake
Primary treatmentsurgical removalsurgical removal
Outlooknearly 100% 5-year relative survival98% 5-year relative survival rate

Symptoms of follicular and papillary thyroid cancer are similar. Symptoms usually don’t appear until the tumor grows large enough to put pressure on other structures in your throat.

General symptoms of thyroid cancer include:

Follicular thyroid cancer usually develops as a solitary mass and is more likely to spread to distant parts of your body. The most common areas this kind of cancer spreads to are:

  • bones
  • lungs
  • soft tissues

About 6% to 20% of people who are given a follicular thyroid cancer diagnosis already have the cancer spread to distant body parts.

For papillary thyroid cancer, about 20% of people develop trouble swallowing or hoarseness. The cancer usually starts as a painless mass.

Thyroid cancer develops when genetic changes in your thyroid cells cause them to replicate beyond control. Doctors usually don’t know why this happens, but they’ve identified some risk factors.

The thyroid is particularly sensitive to radiation exposure because of its position on your neck. It’s thought that the risk of developing cancer remains elevated for more than 50 years after exposure to radiation at a younger age.

Risk factors for papillary cancer

Risk factors for papillary cancer include:

  • radiation therapy exposure, especially during childhood
  • environmental radiation exposure
  • inherited cancer syndromes, in about 5% of cases, such as:
  • regions with higher dietary iodine intake
  • preexisting thyroid disease
  • people who are overweight or have obesity

Risk factors for follicular cancer

Risk factors for follicular cancer are similar and include:

Most thyroid cancers are treated with surgical removal of your thyroid gland. Surgery is the primary treatment for both papillary and follicular thyroid cancer.

If you have your thyroid removed, you’ll need to take thyroid pills to replace your body’s thyroid hormones. If radioactive iodine treatment is part of your thyroid removal therapy, taking hormone replacement pills may be delayed by 6 to 12 weeks after surgery.

Treatment for follicular cancer

Follicular cancer is usually treated by removing the middle and one lobe of your thyroid if the cancer is expected to grow slowly. A doctor may recommend the complete removal of your thyroid gland for more aggressive tumors combined with:

  • Radioiodine remnant ablation: the destruction of thyroid tissue with radioactive iodine
  • Thyrotropin suppressing medication: medications that lower levels of your thyroid hormones by suppressing levels of a hormone called thyroid-stimulating hormone (TSH)

If your cancer has spread to distant body parts, you may also receive treatments such as:

Treatment for papillary cancer

A doctor may recommend the removal of your thyroid gland if you have papillary cancer, but they may recommend removing only one side of your thyroid if the tumor is small.

People with very small cancers may be treated with observation and routine ultrasounds rather than having immediate surgery.

You may receive radioiodine therapy 4 to 6 weeks after the removal of your thyroid if it’s recommended.

People who have papillary thyroid cancer have the best outlook when compared with people who have other types of thyroid cancer. The 5-year relative survival rate for people with papillary thyroid cancer is near 100%.

If the cancer spreads to distant tissues before it’s diagnosed, the relative 5-year survival rate drops to 75%. This means that people with papillary thyroid cancer are 75% as likely to live 5 years as people in the general population.

People with follicular thyroid cancer have a 5-year relative survival rate of about 98%. The survival rate drops to 63% if the cancer spreads to distant areas. Spreading to a distant area is the most serious complication of follicular thyroid cancer.

Follicular and papillary thyroid cancer are the two most common types of thyroid cancer. Both cancers have high survival rates and can often be cured. Follicular cancer is more likely to spread to distant body parts such as your bones or lungs.

The difference between the two cancers is determined mainly by how cells appear under a microscope. Both cancers develop in cells that produce the hormones T3 and T4, which are called “follicular cells.”

Getting a cancer diagnosis is never easy, but getting a thyroid cancer diagnosis in the early stages gives you the best chance of having a good outlook and catching the cancer before it spreads to distant body parts.