Follicular thyroid cancer is a type of cancer that develops in the thyroid cells. Follicular thyroid cancer symptoms can include pain and swelling in the neck, trouble breathing, and more. Treatments can depend on the stage.

The thyroid is a small, butterfly-shaped gland at the front of the neck, responsible for bodily functions such as heart rate, metabolism, and body temperature.

Follicular thyroid cancer is the second most common type of thyroid cancer, accounting for around 10–15% of all thyroid cancers.

According to the American Cancer Society (ACS), in 2022, there were around 43,800 new cases of thyroid cancer in the United States, with more than half of those in females.

In this article, we will discuss follicular thyroid cancer, including symptoms, causes, different types, and treatment options.

When abnormal cells in the thyroid begin to grow uncontrollably, cancer can develop in the thyroid. Follicular thyroid cancer is a tumor of the follicular cells in the thyroid. It is the second most common type of thyroid cancer after papillary thyroid cancer.

The thyroid consists of follicles, which are the structural and functional units of the thyroid. They are responsible for the production and secretion of thyroid hormones.

Follicular cells use iodine from the blood to make thyroid hormones, which contribute to a number of functions in the body, including:

  • regulating metabolism
  • regulating body temperature
  • controlling body weight
  • regulating hunger

Who gets it?

Thyroid cancer is the ninth most common type of cancer worldwide. It is more common in females — the ratio of females to males with the cancer is 3 to 1.

It is also most common in middle-aged people.

Different cancers can develop from different cells in the body. According to the National Health Service (NHS) in the United Kingdom, there are four main types of thyroid cancer, falling under three umbrella categories that are known as differentiated, anaplastic, and medullary:

  1. Papillary carcinoma: This is the most common type of thyroid cancer, in which tumors can grow slowly. It is also highly treatable. It particularly affects women under 40, accounting for around 8 in 10 cases of thyroid cancer.
  2. Follicular carcinoma: Follicular cancer is more aggressive than papillary cancer, and patients over the age of 55 usually have a more malignant disease than younger patients.
  3. Medullary thyroid carcinoma: This type of thyroid cancer is less common, accounting for less than 1 in 10 cases. It is also genetic, meaning that it runs in families.
  4. Anaplastic thyroid carcinoma: This type of cancer is rare and accounts for 1 in 50 cases, mostly affecting those around the age of 60.

Papillary and follicular thyroid cancers are known as differentiated thyroid cancers. Differentiated thyroid cancers usually grow slowly over time.

Learn more about the types of thyroid cancer here.

The symptoms of thyroid cancer, in general, can vary but may include:

  • a lump or swelling in the neck
  • pain in the neck
  • changes to the voice that do not go away
  • trouble breathing
  • trouble swallowing
  • persistent coughing

Learn about the signs of a thyroid disorder here.

There are various causes of follicular thyroid cancer. After the 1986 Chernobyl explosion, thyroid cancer was prevalent among the radiation-induced cancers.

Causes can include:

  • intake of iodine
  • diabetes
  • obesity
  • thyroid issues such as Hashimoto’s thyroiditis
  • radiation exposure such as through X-rays and CT scans

Diet choices also play a role in follicular thyroid cancer, with certain foods having links to an increase in it, such as:

  • chicken
  • pork
  • cabbage
  • broccoli
  • cauliflower

According to the NHS, a person may also have a higher risk of thyroid cancer if a close relative has had it. Thyroid cancer is also more common in those who underwent radiotherapy treatment as a child.

The stages of follicular and papillary thyroid cancer are the same. Staging details the size of a cancerous tumor and whether or not it has spread.

Doctors also use the TNM system, which is as follows:

  • T describes the size of the tumor
  • N signifies the involvement of lymph nodes
  • M signifies metastasis, which means the spreading of the cancer cells to other parts of the body

For people under the age of 55, the staging is:

  • Stage 1: This means a person has thyroid cancer that may or may not have spread to the lymph nodes.
  • Stage 2: This means the cancer has spread to other parts of the body.

Staging for people over the age of 55 is as follows:

  • Stage 1: The cancer is inside the thyroid and measures up to 4 centimeters (cm) long. It has not spread to other parts of the body.
  • Stage 2: This can either mean the cancer has spread, or it is more than 4 cm and has begun to grow outside the thyroid into surrounding muscle or lymph nodes.
  • Stage 3: The cancer has spread into nearby tissue such as the larynx, the trachea or windpipe, the esophagus or food pipe, and the voice box.
  • Stage 4: There are two groups in this stage. 4a means the cancer has spread to the spine or main blood vessels. 4b means it has spread to other parts of the body, such as the lungs.

Seeing or feeling a lump in the neck may be a cause for concern, and a person should contact their healthcare professional for advice. Other symptoms include difficulty swallowing and a change in voice.

Diagnosing follicular thyroid cancer may include a doctor carrying out the following:

  • Biopsy: A biopsy removes a small part of tissue to test for cancerous cells. This may include removing part of the thyroid tissue with a thin needle, such as the thyroid nodule. A biopsy can also determine if it is a benign, or noncancerous, thyroid condition.
  • Imaging tests: This can include a CT scan or X-ray.
  • Blood hormone study: A person’s hormone levels can indicate if there is an underlying issue. High or low levels of thyroid-stimulating hormone (TSH) can point to various conditions, such as hyperthyroidism or hypothyroidism.

Based on their findings, the doctor will work closely with the person to design the most suitable treatment plan.

The treatment of follicular thyroid cancer depends on the stage.

Treatments include:

  • Surgery: There are various types of surgery to treat thyroid cancer, including a thyroidectomy or a lobectomy. A thyroidectomy is the removal of the thyroid to stop further spreading. A lobectomy is a partial removal of the thyroid.
  • Radioactive iodine ablation: This can involve swallowing radioactive iodine in liquid or pill form. The iodine travels through the bloodstream to kill cancerous cells.
  • Thyrotropin suppressing medications: Thyrotropin-releasing hormone is the regulator of thyroid function. Medications that suppress this can help manage thyroid cancer.

Cancer that spreads to bone and soft tissue may also have radiotherapy and chemotherapy as treatment, usually after total thyroidectomy.

As the thyroid gland facilitates many important functions in the body, treatment for follicular thyroid cancer may result in symptoms of an underactive thyroid, also known as hypothyroidism.

Symptoms of an underactive thyroid include:

  • fatigue
  • constipation
  • depression
  • dry hair, skin, and nails
  • having slow movements and thinking
  • muscle aches
  • loss of libido
  • weight gain
  • difficulty sleeping

Learn about treatments for depression here.

Post-treatment management is important to ensure correct healing. A person should:

  • avoid strain on their neck wound
  • avoid driving for around a week after surgery, especially if taking strong painkillers
  • engage in gentle neck exercises, as directed by a physiotherapist after surgery

The survival rate refers to the proportion of people who are still alive for a length of time after receiving a particular diagnosis. For example, a 5-year survival rate of 50% means that 50%, or half, of the people are still alive 5 years after receiving the diagnosis.

It is important to remember that these figures are estimates and are based on the results of previous studies or treatments. A person can consult a healthcare professional about how their condition is going to affect them.

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The outlook or survival rate can help understand how long a person may live after diagnosis and treatment for a condition.

According to the ACS, the survival rate for follicular thyroid cancer is as follows:

Type of follicular thyroid cancer Survival rate
localized, meaning cancer has not spread beyond the lymph nodenearly 100%
regional, which means cancer has spread to nearby structures98%
distant, meaning cancer has reached other parts of the body63%
all stages combinednearly 98%

Outlook and treatment can depend on many factors, such as:

  • the stage of the cancer
  • the age of the person
  • whether treatment has led to the complete removal of the cancer
  • whether the cancer has returned

Finding support while undergoing treatment for cancer can be an important step.

A few organizations that can help are:

A person should contact a healthcare professional if symptoms occur, such as noticing a lump on their neck or enlarged lymph nodes.

Follicular thyroid cancer is the second most common type of thyroid cancer and is the ninth most common cancer worldwide.

Symptoms can include a lump on the neck or enlarged lymph nodes. Treatment depends on the stage and can include surgery, radioactive iodine, or chemotherapy if the cancer has spread.

Anyone who notices enlarged lymph nodes in the neck or a lump in or on the neck should consult a doctor.