What is Anaplastic Thyroid Cancer?
Anaplastic thyroid carcinoma (ATC), also known as undifferentiated carcinoma, is a rare and extremely aggressive type of cancer that makes up about 2% to 3% of all thyroid gland tumours. It’s important to know that ATC is one of the deadliest diseases globally and has a very bad prognosis, which means the disease’s outcome or the likelihood of recovery is very low.
ATC is characterized by substantial local spread and often spreads to the lymph nodes in the neck and other distant parts of the body. This makes the disease very dangerous and the death rate almost 100 percent. Unfortunately, most patients are only diagnosed when the disease has already spread to other parts of the body.
Even though the situation with ATC seems grim, recent advances in understanding ATC’s genetic and molecular causes gives hope for specific treatments for this deadly disease. These targeted treatments aim at the precise causes of cancer, offering a spark of hope.
What Causes Anaplastic Thyroid Cancer?
Based on a study by Zivaljevic and his team, the conditions that increase the chance of developing anaplastic thyroid cancer (ATC) are lower levels of education, having a blood type B, and having a goiter (enlarged thyroid). Also, more challenging and negative medical findings tend to be associated with a type of thyroid cancer that is hard to treat if the person is older, male, has advanced disease in the area around the tumor, or the cancer has spread to distant parts of the body.
Risk Factors and Frequency for Anaplastic Thyroid Cancer
Anaplastic thyroid cancer (ATC) is more common in regions where goiter, a condition related to the thyroid gland, is widespread. In the United States, ATC accounts for 1.7% of all thyroid cancers. However, this rate varies by location, with some areas recording rates between 1.3% and 9.8%.
- Most ATC patients are older, often in their sixties or seventies.
- The average age when people are diagnosed with ATC is 65.
- Women are twice as likely to get ATC as men.
- The instances of ATC remained consistent from 1973 to 2002 according to data from the surveillance, epidemiology, and results database.
Signs and Symptoms of Anaplastic Thyroid Cancer
Anaplastic thyroid cancer usually presents itself in a few common ways:
- A quick-growing, firm lump in the front lower part of the neck, often attached to the tissue beneath it
- Pressure-related symptoms such as hoarseness, difficulty swallowing, shortness of breath, and cough
- About 40% of cases spread to nearby lymph nodes and about 30% involve vocal cord paralysis
Testing for Anaplastic Thyroid Cancer
An ultrasound examination might show some typical signs of anaplastic thyroid carcinoma (ATC) which include solid lumps, decreased echo-producing soundwaves (marked hypoechogenicity), irregular borders, calcium build-ups (internal calcification), shapes that are broader than they are tall, and signs of spread to the nearby cervical lymph nodes.
Your doctor may suggest a fine-needle aspiration (FNA) or biopsy which involves removing a small sample of cells from your thyroid with a thin needle to examine under a microscope. However, just to be sure, this cancer must also be confirmed by examining more tissue from a surgical biopsy or from a piece removed during surgery. On close examination, ATC cells appear different to normal thyroid cells and typically show signs of rapid cancer growth and cell death.
Intraoperative consultation is where your tissue sample can be quickly examined during surgery to guide decision-making during the procedure itself.
A computed tomography scan, or CT scan, might be used to define the extent of ATC and determine if the cancer has spread to the lymph nodes. This imaging technique usually shows ATC as large masses that are either the same density (isodense) or slightly denser (hyperdense) than muscle tissue. There might also be signs of calcification and tissue necrosis (cell death) which often suggests that the cancer is advanced.
Magnetic resonance imaging (MRI) can also be helpful in determining how far the cancer has grown, especially if it has spread to the esophagus muscles, the trachea (your windpipe), or the carotid vessels (major blood vessels in your neck).
Your doctor may also suggest a particular scan known as an F-fluorodeoxyglucose positron emission tomography (FDG-PET) scan. This imaging technique can be especially useful for ATC because these cancer cells take up more glucose (sugar) than normal cells due to higher levels of a protein called glucose transporter (GLUT-1). This allows the scan to effectively highlight areas of the body where these cancer cells are present.
Treatment Options for Anaplastic Thyroid Cancer
A common treatment option for anaplastic thyroid cancer (ATC) – a severe form of thyroid cancer – is surgery (if possible) and chemoradiation. Chemoradiation involves the use of chemotherapy drugs and radiation therapy either at the same time or one after the other. The vast majority of ATC cases can’t be removed surgically when first diagnosed due to the cancer spreading to nearby neck structures. However, surgery is used to help maintain a clear airway for the patient.
Debulking surgery is often performed. This operation aims to remove as much of the tumor as possible, mainly if it threatens the airway and may affect the voice box (larynx). In some instances, a tracheostomy – a procedure to cut an opening in the windpipe to allow breathing – may be necessary if the airway is compromised (blocked or narrowed). Though removing the entire tumor is often impossible because the disease has spread, the amount of tumor that is successfully removed can impact a patient’s survival chances.
Radiation therapy, a treatment that uses high-energy rays to destroy cancer cells, and chemotherapy, using drugs to kill cancer cells, are often recommended for patients with advanced ATC that can’t be removed through surgery. Even if the tumor was entirely removed or was small to begin with, radiation therapy is typically used afterward as an extra precaution. Generally, ATC doesn’t respond well to I131 therapy – the use of radioactive iodine to target and kill cancer cells. This form of treatment is only used if the cancer has something called a “differentiated iodine-positive component,” meaning some areas of the cancer might take up and react to the iodine.
New research is helping us learn more about the biology and genetics of ATC, which might open the door to new, more effective therapies in the future.
What else can Anaplastic Thyroid Cancer be?
When doctors try to figure out if a patient has anaplastic thyroid cancer, there are other illnesses with similar indicators they must consider. These are:
- Metastatic disease to the thyroid, such as metastatic clear-cell renal carcinoma
- Primary thyroid lymphoma
- Primary thyroid sarcoma
- Poorly differentiated thyroid carcinoma
- Squamous cell thyroid carcinoma
- Medullary carcinoma
What to expect with Anaplastic Thyroid Cancer
Anaplastic thyroid cancer (ATC) is a type of cancer that usually doesn’t improve with various treatments. Recent large-scale research covering the period from 1986 to 2015, shows that the average survival period is four months, and only 35% of people survive six months after diagnosis. Only 12% survive more than two years.
Some factors can improve survival chances for those with ATC. These include being younger than 60 years old, not having cancer spread to the neck region or other parts of the body, having small tumors that are less than 5 to 7 cm, having the tumor on one side of the body only, not having the cancer spread into surrounding tissue or to lymph nodes, and finding the ATC unexpectedly during a surgical procedure to remove the thyroid gland.
Possible Complications When Diagnosed with Anaplastic Thyroid Cancer
In about 70% of cases, the disease spreads to nearby areas including muscles (in 65% of cases), trachea (46%), esophagus (44%), laryngeal nerve (27%), and larynx (13%). Also, approximately 40% of patients experience the disease spreading to their lymph nodes. This condition progresses quite quickly, and sadly, the majority of patients pass away within a year due to the disease blocking their airways or complications from it spreading to their lungs. The disease can also spread to other parts of the body in up to 75% of patients, especially the lungs (80% of those cases), brain (5-13%) and bones (6-15%).
Spread of the Disease:
- Neighbouring areas (70% of patients), which includes:
- Muscles (65% of these cases)
- Trachea (46% of these cases)
- Esophagus (44% of these cases)
- Laryngeal nerve (27% of these cases)
- Larynx (13% of these cases)
- Lymph nodes (40% of patients)
- Lung complications due to disease progression (most within 1 year)
- Spread to other parts of the body (75% of patients), particularly:
- Lungs (80% of these cases)
- Brain (5-13% of these cases)
- Bones (6-15% of these cases)
