Anaplastic Thyroid Cancer Overview

A rare, aggressive form of the disease

Updated on October 09, 2022

Medically reviewed by Oliver Eng, MD

Anaplastic thyroid cancer (ATC) is a fast-growing and aggressive type of thyroid cancer. Also known as undifferentiated thyroid cancer, the disease involves the rapid division of cancer cells that don't or barely resemble or act like normal thyroid cells.

Anaplastic cancers can grow as quickly as several weeks and can cause severe compression of the structures in the neck, interfering with breathing, swallowing, and speaking. It can also metastasize (spread) rapidly throughout the body.

Symptoms of Anaplastic Thyroid Cancer

The first signs of anaplastic thyroid cancer are typically related to the enlargement of the thyroid gland—a bow-tie-shaped endocrine gland located in the neck, below the Adam's apple area.

While this type of cancer can cause symptoms of thyroid disease, such as weight loss or fatigue, these symptoms are not usually among the earliest signs of the condition.

The early signs and symptoms of anaplastic cancer include:

A mass in the neck that you can both see and feel
Rapid enlargement of the thyroid gland
A large lump on the thyroid gland
Swollen lymph nodes in the neck
Hoarseness or a change in the voice
Cough
Coughing up blood
Difficulty swallowing
Trouble breathing

Anaplastic thyroid cancer can quickly infiltrate the trachea (windpipe), interfering with breathing. ATC is also one of the only types of thyroid cancer that can rapidly spread to other areas of the body.

Performing a Thyroid Neck Check: Step-by-Step

What Causes Anaplastic Thyroid Cancer?

The cause of anaplastic thyroid cancer is not known, but there are several risk factors that have been identified.

Previous thyroid cancer or enlargement: Most people diagnosed with anaplastic thyroid cancer also had another type of less aggressive thyroid cancer or an enlarged thyroid prior to developing ATC. It is not clear why these tumors increase the risk of developing ATC.
Radiation: A history of radiation exposure to the thyroid region is also among the risk factors associated with ATC.
Genetic mutations: There have been several genetic mutations identified in association with this disease. The genetic abnormalities identified in ATC are not believed to be hereditary (i.e., run in families) and may develop at some point during life. There is no clear association between the genetic mutations found in ATC and disease prognosis, cause, or screening.

Diagnosis

If you have symptoms of neck compression due to thyroid enlargement, your diagnostic evaluation will include neck imaging studies, such as ultrasound, a computed tomography (CT) scan, or magnetic resonance imaging (MRI) of your neck and surrounding regions.

A diagnostic evaluation of a thyroid growth usually involves a biopsy as well. A biopsy is a sample of thyroid tissue, usually taken with a thin needle, that is then examined under a microscope. This is a minor surgical procedure that requires an injection of local pain medication. After the procedure, you will need stitches for your wound.

A biopsy sample of anaplastic thyroid cancer shows undifferentiated thyroid cells. They are not as well developed as regular thyroid tissue and appear less like well-functioning thyroid tissue than samples of other thyroid tumors.

Thyroid Cancer Doctor Discussion Guide

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Stages of Anaplastic Thyroid Cancer

As part of the diagnostic process, ATC is also staged. The disease is defined by how much it has invaded the body.

The stages of anaplastic thyroid cancer are:

Stage IVA: The cancer is only found in the thyroid gland.
Stage IVB: The cancer has spread outside the thyroid gland to other areas of the neck.
Stage IVC: The cancer is metastatic and has spread to distant areas of the body through the bloodstream.

ATC typically metastasize into the trachea, lymph nodes, lungs, and bones. In as many as 25% of cases, infiltration of the trachea is already present at the initial diagnosis of the condition.

The spread of ATC to the bones, lungs or brain is estimated to have already occurred in as many as 50% of cases by the time of ATC diagnosis.

Anaplastic Thyroid Cancer Treatment

Unfortunately, the prognosis for ATC is very poor, with only half of people surviving 6 months after diagnosis. However, treatment can prolong survival, and, in rare instances, the condition can be cured.

Treatment of anaplastic thyroid cancer is focused on relieving the compression caused by the tumor, supportive control of symptoms, and radiation and chemotherapeutic treatment to control the growth of the cancer in the neck and elsewhere in the body.

There are several treatment approaches:

Surgery: Anaplastic thyroid cancer is often treated with surgery to remove the tumor from the thyroid gland and, if applicable, any surrounding structures the tumor has invaded. Sometimes ATC becomes attached to vital structures within the neck and may, unfortunately, be inoperable.
Supportive care for symptoms: If ATC infiltrates your windpipe, a tracheostomy (a surgical procedure done to insert a tube that then serves as an airway) may be necessary to ease breathing.
Radiation and chemotherapy: Radiation is often needed to shrink the tumor in the neck and elsewhere in the body. Chemotherapy is used to treat metastatic disease. However, remains of the anaplastic thyroid cancer tumor within the thyroid gland are not typically responsive to chemotherapy.
Gene therapy: There are new treatment approaches that are currently being investigated for ATC treatment. They use targeted chemotherapy that is personalized for treatment of the specific molecular defects caused by the genetic mutations associated with anaplastic thyroid cancer. This approach is currently considered investigational.

Because there are not many available or effective treatments for ATC, you may also decide to participate in a clinical trial, potentially gaining access to new treatments that could be more beneficial than those currently available.

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A Word From Verywell

A diagnosis of an aggressive form of cancer, like anaplastic thyroid cancer, is among the most difficult challenges that a person or a family can face.

Deciding which treatment approach to take depends on whether you can tolerate the recovery process after surgery and whether you are prepared to devote your time and energy to treatment with radiation and chemotherapy.

Speak with your healthcare provider about your options and any concerns.

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