What is thyroid cancer ?
- Thyroid cancer is a cancer that begins in the thyroid. Cancer begins when cells begin to grow or change beyond mutation. Abnormal cells begin to multiply in the thyroid gland when enough of them form a tumor.
- A tumor may be cancerous or benign. A malignant cancer tumor can grow and spread to other parts of the body. A benign tumor means the tumor may grow but will not spread. Thyroid tumors can also be called nodules, and about 90% of all thyroid nodules are benign.
Types of thyroid cancer
Differentiated thyroid cancer
Most thyroid cancer is cancer differentiated and has grown from thyroid follicular cells.
Differentiated types of thyroid cancer:
- Papillary carcinoma: about 8 out of 10 thyroid cancers are papillary cancer. The disease develops very slowly and usually develops only in one lobe of the thyroid gland. Although slow growing, papillary cancer usually spreads to the lymph nodes in the neck.
- Cancer carcinoma follicular: about 1 in 10 thyroid cancer usually does not spread to the lymph nodes, but they can spread to other parts of the body, such as the lungs or bones.
- Hurthle cell carcinoma: accounts for about 3% of thyroid cancers, rare and difficult to treat.
Medullary thyroid cancer
Approximately 4% in all types of thyroid cancer.
- Medullary cancer begins in thyroid cells called C cells that produce the hormone calcitonin, a hormone that helps control the amount of calcium in the blood. Elevated levels of calcitonin in the blood can indicate medullary thyroid cancer at a very early stage.
- Sometimes this cancer can spread to lymph nodes, lungs or liver even before a thyroid nodule is detected.
There are 2 types of medullary thyroid cancer:
- Sporadic MTC : accounts for about 8 out of 10 MTC cases
- Family MTC : inherited and 20% to 25% can occur in each generation of a family.
Anaplastic thyroid cancer (regardless)
- As advanced thyroid cancer it invades other parts of the body and is found in less than 2% of patients with thyroid cancer.
- Very rare Anaplastic thyroid cancer grows fast and is difficult to treat. Usually occurs in adults aged 60 years and up.
Less common thyroid cancer : Less than 4% of the cancer found in the thyroid gland is thyroid lymphoma, thyroid sarcomas or other rare tumors.
Causes of thyroid cancer
Thyroid cancer occurs when cells in the thyroid gland undergo genetic changes. Mutations allow cells to grow and multiply quickly. The cells also lose the ability to die, abnormally accumulating to form a tumor which then invades nearby tissue and can spread throughout the body.
Factors that can increase the risk of thyroid cancer include:
- Gender and age: Thyroid cancer occurs about 3 times more often in women (ages 40 – 50) than men (ages 60 – 70).
- Exposure to high levels of radiation: Exposure to high levels of radiation includes treatment of radiation to the head, neck and fallout from sources such as nuclear power plant accidents or possible weapons testing. potential to cause thyroid cancer.
- Certain genetic syndromes: Genetic syndromes that increase the risk of thyroid cancer include familial and medullary thyroid cancer.
- Other thyroid conditions: such as thyroiditis or goiter
- Iodine in the diet
- Genetic: medullary thyroid cancer is sometimes caused by a change in a gene passed from parent to child.
- Breast cancer: breast cancer survivors may be at higher risk for thyroid cancer, especially in the first 5 years after diagnosis and for those diagnosed with breast cancer at younger age.
Symptoms of thyroid cancer
Thyroid cancer usually does not cause any early signs or symptoms in the disease. It is sometimes found during a regular physical exam.
When thyroid cancer develops, it may have signs:
- A lump can be felt through the skin on the neck
- Voice changes include hoarseness
- Difficulty swallowing
- Pain in the neck and throat
- Swollen lymph nodes in the neck
- Shortness of breath
- Thyroid cancer can affect the production of thyroid hormones and cause diarrhea and hot flashes.
Many of these symptoms can also be caused by conditions other than cancer or even other cancers in the neck area.
Tumors in the thyroid are common and often benign. However, if you have any of these signs or symptoms, talk to your doctor right away so you can find out and treat the cause if needed.
Diagnosis of thyroid cancer
The thyroid, neck and blood tests are used to detect and diagnose thyroid cancer:
- General health check
- Research hormones in the blood
- Studying blood chemistry
- CT scan
- Fine needle biopsy of the thyroid gland
- Biopsy surgery
The treatment options depend on the type and stage of thyroid cancer, your overall health and your preferences.
The standard treatment types used
Surgery is the main treatment in nearly every case of thyroid cancer, with the exception of some anaplastic thyroid cancers.
Activities used to treat thyroid cancer include:
- Removal of all or most of the thyroid gland (thyroidectomy).
- Removal of lymph nodes in the neck.
- Removal of a part of the thyroid gland (lobectomy).
Radiotherapy and radioactive iodine therapy
- Radiotherapy is a treatment for cancer that uses high-energy X-rays or other types of radiation to kill cancer cells or keep them from growing.
- Radioactive iodine treatment is usually recommended after surgery. This will help destroy any remaining cancer cells in your body and reduce the risk of cancer coming back.
Thyroid hormone therapy
- After a thyroidectomy, you will take levothyroxine thyroid hormone medicine for life.
- The drug provides the missing hormone that your thyroid usually produces and it blocks the production of thyroid stimulating hormone (TSH) from the pituitary gland which slows the growth of any remaining cancerous cells.
- Chemotherapy is a drug that uses chemicals to kill cancer cells. Chemotherapy is usually given in the form of intravenous infusion. The chemicals travel throughout the body to destroy rapidly growing cells including cancer cells.
- Chemotherapy is not commonly used in the treatment of thyroid cancer but it may be beneficial for some people who do not respond to other treatments. For people with chemotherapy anaplastic thyroid cancer may be combined with radiation therapy.
- Targeted therapy is a treatment that targets specific genes, proteins of the cancer or tissue environment that contribute to cancer growth and survival. This type of treatment prevents the growth and spread of cancer cells while limiting damage to normal cells.
- There are different types of targeted therapies: Tyrosine kinase inhibitor, Protein kinase inhibitor.
- Targeted drugs used to treat thyroid cancer include: Cabozantinib, Sorafenib (Nexavar), Vandetanib (Capreba)
Metastatic thyroid cancer
- Cancer that has spread beyond the thyroid to other organs such as: bone or lung is called metastatic thyroid cancer. Also all anaplastic thyroid tumors are classified as stage IV at the time of diagnosis regardless of tumor size, location or spread.
- If the diagnosis is stage IV thyroid cancer, talk to experienced doctors. Doctors may have different opinions about the best standard treatment plan.
- Your treatment plan may include a combination of surgery, hormone therapy, radioactive iodine therapy, external beam radiotherapy, targeted therapy and chemotherapy. Palliative care is also important to help reduce symptoms and side effects
- The outlook for differentiated thyroid cancer is very good. Most people (80-90%) will have a normal life expectancy.
- Papillary and follicular carcinomas tend to grow slowly and are relatively simple to treat.
- More than 9 in 10 people with papillary carcinoma will live 10 years or more after diagnosis. More than 8 in 10 people with thyroid cancer will live at least 10 years after being diagnosed.
- Medullary thyroid cancer is more difficult to treat. It is unresponsive to iodine therapy so removing all cancer cells can be difficult.
- The survival rate for medullary adenocarcinoma depends on the stage of the cancer when diagnosed. If diagnosed at an early stage, 97% of people live at least 5 years after diagnosis.
- If medullary thyroid cancer is diagnosed after it has spread to other parts of the body, 1 in 4 people will live for at least 5 years after diagnosis.
- Because of its more serious nature, fewer than 1 in 10 people with anaplastic thyroid carcinoma will live at least 5 years after being diagnosed.
Source Reference Thyroid cancer:
- Source mayoclinic.org article Thyroid Cancer : https://www.mayoclinic.org/diseases-conditions/thyroid-cancer/symptoms-causes/syc-20354161 , updated March 14, 2019.
- Source webmd.com article What Is Thyroid Cancer? : https://www.webmd.com/cancer/what-is-thyroid-cancer#1 , updated 9/14/2018.
- Reputable sources index-china.com synthesis article What is Thyroid cancer?: https://index-china.com/thyroid-cancer/, updated 14/3/2019.
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