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What is Anaplastic Thyroid Cancer?
Anaplastic thyroid cancer (ATC), also known as undifferentiated thyroid cancer, is one of the most aggressive and dangerous types of cancer. The cancer cells in this type of cancer do not have a structure and function similar to normal thyroid cells. Normally, thyroid cells undergo a process called differentiation to become mature, specialized cells that perform specific functions in the body. However, in this differentiated thyroid cancer, this differentiation process is disrupted and the cells remain immature and abnormal. Anaplastic thyroid cancer is very rare, accounting for only 1 to 2 percent of all thyroid cancers. It is more common in older people (with an average age of about 60 years) and in women.
Causes of anaplastic thyroid cancer
The exact cause of anaplastic thyroid cancer is not yet fully understood, but it is likely a combination of genetic and environmental factors. Most often, there is a problem with the thyroid gland before this cancer starts. This cancer can develop in an enlarged thyroid gland (goiter). A previous history of differentiated thyroid cancer (such as papillary or follicular cancer) can also be a cause of this cancer. In many cases, anaplastic thyroid cancer develops from a previous differentiated cancer that was not properly treated or has progressed.
Stages of anaplastic thyroid cancer
The stage of a cancer describes the size of the tumor and the extent to which it has spread to other parts of the body. In other words, the stage of the cancer indicates how far the disease has progressed. The staging system for cancers is usually determined by the size of the tumor and the extent to which it has spread to lymph nodes and other organs. But because anaplastic thyroid cancer is aggressive and spreads quickly, its staging is different from other cancers.
In anaplastic thyroid cancer, the size of the tumor or the presence of lymph node metastasis does not play a role in determining the stage of the cancer. In fact, all anaplastic thyroid cancers are considered stage IV (four) because they have usually spread to the tissues around the thyroid and the lymph nodes in the neck at the time of diagnosis. The only factor that matters in determining the stage of this cancer is whether it has spread to distant organs, such as the lungs, liver, or bones.
According to the American Thyroid Association (ATA) thyroid.org website, the stages of anaplastic thyroid cancer are as follows:
Stage IVA: Only the thyroid gland and nearby lymph nodes are involved, and other organs have not yet been infected.
Stage IVB: Cancer is present in the thyroid gland and neck tissues, but has not yet spread to other parts of the body.
Stage IVC: Cancer has spread beyond the thyroid to other parts of the body, such as the bones, lungs, or brain.
In about 10 percent of patients, anaplastic thyroid cancer is found only in the thyroid gland. In about 40 percent of diagnosed cases, the cancer is localized to the neck or lymph nodes. In other patients, anaplastic thyroid cancer has metastasized to other parts of the body at the time of diagnosis.
Symptoms of anaplastic thyroid cancer
Anaplastic thyroid cancer often appears as a lump or nodule in the thyroid gland at the front of the neck. ATC tumors grow very quickly and are usually noticeable to the person with ATC or their family and friends. The tumor is usually painful and hard. As the tumor grows too large, it presses on other structures in the neck and causes the following symptoms:
- Difficulty swallowing (dysphagia)
- Difficulty breathing (dyspnea)
- Hoarseness or voice changes
- Persistent cough, with or without blood
- Vocal cord paralysis
People with advanced (metastasized) anaplastic thyroid cancer may also have the following symptoms:
- Bone pain
- Swollen lymph nodes
- Weakness
- Nerve problems
Risk factors for anaplastic thyroid carcinoma
Some factors can increase the risk of developing anaplastic thyroid cancer. The most important risk factors for this disease are:
Age: Most cases of anaplastic thyroid cancer occur in people between the ages of 60 and 70.
Gender: Women are more likely to develop this type of cancer than men.
Medical history: A history of goiter or other thyroid cancers increases the risk of developing anaplastic thyroid cancer.
Radiation exposure: A history of radiation therapy to the head and neck or exposure to radioactive materials increases the risk of developing anaplastic thyroid cancer.
Blood type: Studies show that people with blood type B are at a higher risk of developing this cancer.
Diagnosing Anaplastic Thyroid Cancer
Anaplastic thyroid cancer can spread quickly, over a few weeks. So it’s important to see a doctor right away. Your doctor will examine you to check for any lumps or tumors in your neck.
Diagnostic tests commonly used for anaplastic thyroid cancer include:
Thyroid biopsy:
In a thyroid biopsy, a sample of thyroid gland tissue is removed using a needle to be examined under a microscope for cancer cells.
Imaging tests:
Such as an MRI or CT scan.
Laryngoscopy:
In this procedure, the airways are examined through a special scope that is inserted into the throat.
Thyroid scan:
This test shows whether the tumor absorbs radioactive material. If the tumor does not absorb radioactive material, it means it is cancerous.
Anaplastic Thyroid Cancer Treatment
Anaplastic thyroid carcinoma (ATC) is difficult to treat because of its highly aggressive nature and ability to spread rapidly in the neck and to distant parts of the body, including the lungs, bones, and brain. Treatment for ATC usually involves a combination of the following:
Thyroid surgery:
If you have anaplastic thyroid cancer, your doctor may recommend surgery to remove the tumor, unless you have other medical conditions that increase your risk of surgery. Debulking surgery is the most common treatment for ATC.
This surgery is done to preserve your larynx. In this procedure, your doctor will surgically remove as much of the tumor as possible, especially any part of the tumor that may be threatening your airway. Unfortunately, in many cases, surgery is not possible because of the large size, location, and aggressiveness of the tumor. However, many people with ATC who are not eligible for surgery have been able to live for several years after treatment by receiving a combination treatment that includes chemotherapy and radiation therapy.
Dr. Ahmad Fanaei is a thyroid and parathyroid surgeon and a member of the American Thyroid Association. Known as the Golden Claw Thyroid Surgeon, he has performed over 5,000 successful thyroid surgeries and over 20 years of surgery. To schedule an appointment and consultation, you can fill out the online appointment booking form or call the numbers listed.
Radiation therapy:
This is usually the main treatment for anaplastic thyroid cancer and may be given alone, after surgery, or in combination with chemotherapy. Radiation therapy uses rays (strong beams of energy) to kill cancer cells or stop them from growing and dividing. In most cases, your doctor will recommend a special type of radiation therapy called external beam radiation therapy (EBRT). This treatment directs precise, focused X-rays to the areas that need treatment (often the tumor itself or cancer that has spread to the bones or other organs).
Chemotherapy:
Chemotherapy can be given alone or in combination with surgery or radiation therapy. Chemotherapy for anaplastic thyroid cancer is a type of cancer treatment that works by destroying cancer cells and preventing them from multiplying, and is usually recommended as an adjuvant treatment. This means that chemotherapy is given after surgery or radiation therapy to kill any remaining cancer cells.
Chemotherapy for ATC essentially enhances radiation therapy to make the cancer more sensitive to radiation or to make it more effective. Chemotherapy drugs rarely completely cure advanced cancers that have spread widely throughout the body, but they can slow or partially reverse the growth of the cancer.
Chemotherapy drugs used for anaplastic thyroid cancer include taxanes (paclitaxel or docetaxel), anthracyclines (doxorubicin), and platinum analogs (cisplatin or carboplatin).
Targeted therapy:
Targeted therapy is a new approach to fighting cancer that targets specific weak points in cancer cells to destroy them.
Immunotherapy:
Immunotherapy drugs are sometimes used to help control anaplastic thyroid cancer.
Palliative care:
Palliative care involves medical care that relieves pain, symptoms, and stress caused by serious illnesses. Palliative care is recommended to manage ATC symptoms and side effects of treatment and may include:
- Placing a tube in your throat to help you breathe (tracheostomy)
- Placing a feeding tube in your stomach (gastrostomy tube or G-tube)
- Giving you pain medication
Outlook for anaplastic thyroid cancer
Anaplastic thyroid cancer is highly aggressive, and most people with it live only a few months after diagnosis. The 5-year relative survival rate is 7%. This means that 7 out of 100 people will survive at least 5 years after their diagnosis. Survival rates vary greatly depending on how far the cancer has spread. If the cancer is localized and limited to the thyroid, your 5-year relative survival rate is 39%.
For regional cancers that have spread beyond the thyroid to nearby areas, 11 out of 100 people will be alive within 5 years. However, if the cancer has spread to bones or other distant organs, the survival rate drops to 4%.
Bottom Line:
Anaplastic thyroid cancer is the rarest type of thyroid cancer, more common in women, and usually affects people over the age of 60. This aggressive cancer progresses much faster than other types of cancer, so early detection and timely initiation of treatment are essential.
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