What Is Anaplastic Thyroid Cancer? Symptoms, Treatment and Disease Course

What Is Anaplastic Thyroid Cancer?

• The thyroid is a butterfly-shaped gland at the front of the neck. It secretes thyroid hormones that regulate body temperature, heart rate, blood pressure and weight.
• Anaplastic thyroid cancer is an undifferentiated tumor arising from follicular epithelial cells that produce thyroid hormones.
• Rare cancers include this disease.
• Anaplastic thyroid cancers spread very rapidly, and more than half of patients are around stage 4 at diagnosis.
• Diagnosis is generally made through biopsy, with pathological examination under a microscope.
• Surgery, radiotherapy, chemotherapy, smart medicines called tyrosine kinases and combinations of these are used to treat anaplastic thyroid cancer.

Who Develops Anaplastic Thyroid Cancer? (Age and Sex Distribution)

• Anaplastic thyroid cancer accounts for less than %5 of all thyroid cancers.
• Approximately 70-80 thousand new cases of anaplastic thyroid cancer are thought to occur worldwide annually.
• It mostly occurs at age 65 and older.
• It is 2 times more common in women than men.

What Are the Risk Factors for Anaplastic Thyroid Cancer?

• Age: Risk increases after age 65.
• Personal or family history of goiter: Most people with this cancer type have been found to have long-standing goiter.
• Radiation exposure: Exposure to radioactive substances or previous head and neck radiotherapy increases thyroid cancer risk.

Note: Having a risk factor does not necessarily mean cancer will develop; it only indicates a greater likelihood than in people without that factor.

What Causes Anaplastic Thyroid Cancer?

Anaplastic thyroid carcinoma is thought to arise from other long-standing, previously undetected thyroid cancers (such as papillary or follicular). It has genetic associations with the oncogenes C-myc, H-ras and Nm23. Mutations have also been found in tumors of people with anaplastic thyroid cancer in BRAF, RAS, catenin (cadherin-associated protein), beta 1, PIK3CA, TP53, AXIN1, PTEN and APC genes, and chromosomal abnormalities are common.

What Are the Symptoms of Anaplastic Thyroid Cancer?

• The first sign is often a neck mass.
• Bloody sputum
• Difficulty swallowing or breathing
• Hoarseness or voice changes
• Rapid weight loss due to appetite loss

How Is Anaplastic Thyroid Cancer Diagnosed?

• Biopsy is essential for diagnosis and is performed under ultrasound guidance.
• Radioactive iodine is used to obtain a radiological image of the thyroid gland.
• Fine-needle aspiration biopsy is standard; when insufficient, excisional biopsy should be preferred.

After anaplastic thyroid cancer is diagnosed, other scans and tests may help determine nodule size, location and spread.

These tests include:

• Computed tomography, PET-CT and magnetic resonance imaging
• Chest X-ray
• Laryngoscopy or fiber-optic examination may be performed to determine whether the vocal cords are affected.

How Is Anaplastic Thyroid Cancer Treated?

• Because anaplastic thyroid tumors grow and spread rapidly, emergency tracheostomy may be required. Tracheostomy is an opening made into the windpipe from outside.
• If at diagnosis the tumor has not spread to distant organs but cannot be removed surgically, radiotherapy and/or chemotherapy are used to try to shrink it.
• Radioactive iodine treatment has no role in anaplastic thyroid cancer.

Treatment methods should be individualized according to the following factors;

• Age
• Tumor size
• Extent of cancer spread

Anaplastic thyroid cancer has 3 main treatment methods: Surgery, radiotherapy and chemotherapy

1. Thyroid cancer surgery: The thyroid gland can be completely removed through thyroidectomy. This procedure is performed only when cancer is confined to the thyroid or to reduce cancer-related symptoms.
2. Radiotherapy and Chemotherapy
   • Radiotherapyis generally given to shrink the tumor before surgery (neoadjuvant) and reduce the likelihood of recurrence after surgery (adjuvant). Some tumors cannot be cleared with surgery alone, but radiation may make this possible. It may also be given to relieve symptoms in metastatic disease (palliative treatment).
   • Chemotherapyis given to kill cancer cells in the body or slow cancer spread. It is administered through the bloodstream and may help reduce pain. Chemotherapy medicines used for anaplastic thyroid cancer include doxorubicin (adriamycin), cisplatin, docetaxel and paclitaxel. Doxorubicin is an anthracycline cancer medicine and is probably the most effective chemotherapy medicine for metastatic thyroid cancer.
3. Targeted smart medicines: BRAF mutations have been identified in %30-50 of thyroid cancers. Although not yet FDA-approved, evidence that BRAF-targeted treatment may be effective in anaplastic thyroid cancer was reported in a study published in October 2017. Another targeted medicine, the mTOR inhibitor everolimus, may also be used as palliative treatment in metastatic disease.

What Is the Prognosis (Disease Course) of Anaplastic Thyroid Cancer?

Although anaplastic thyroid cancer accounts for less than %5 of thyroid cancers, it causes %50 of thyroid cancer deaths. Median survival in patients with this disease is approximately 6 months. Therefore, in anaplastic thyroid cancer, palliative treatmentshave an important role from diagnosis onward. A tracheostomy tube may allow comfortable breathing, and gastrostomy (a feeding tube placed in the stomach) may facilitate nutrition.