Thyroid Cancer

Original Editors - Adam Hooten & Andrew Stethen from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Adam Hooten, Andrew Stethen, Lucinda hampton, Kim Jackson, Vidya Acharya, WikiSysop, Elaine Lonnemann, 127.0.0.1, Wendy Walker and Adam Vallely Farrell  

Introduction

Thyroid cancer is a malignancy arising from the thyroid parenchymal cells.

• Its incidence is steadily increasing worldwide while the mortality rate has remained stable over the past several years.
• The clinical behavior of thyroid cancer is highly variable ranging from indolent slowly progressing tumors to highly aggressive tumors with high mortality rates.

Epidemiology

Thyroid Cancer represents 1% to 4% of all malignancies and is the fifth most common cancer in women in the United States. Females are more commonly effected than male (around 3:1).

There has been a steady rise in the incidence of thyroid cancer globally, in both genders and among all races and is thought to be primarily due to an increasing trend in the rate of diagnostic imaging. PTC is the most common endocrine cancer and is responsible for 96% of all new and 66.8% deaths due to endocrine cancers.[20] As was mentioned earlier, most thyroid cancers are derived from the follicular epithelium, with PTC and FTC being far more common than anaplastic thyroid cancer.

Estimated new cases in the United States in 2014: 62,980 (47,790 in women and 15,190 in men).

Estimated deaths in the United States in 2014: 1,890 (1,060 women and 830 men).

Thyroid cancer is more commonly diagnosed at a younger age than most other adult cancers. Nearly 70% of new cases are found in people younger than 55 and about 2% are found in children and teens. Thyroid cancer diagnoses have increased in the recent years and is the most rapidly increasing cancer in the United States. This increase can mostly be attributed to the advances in the thyroid ultrasound which can detect very small thyroid nodules. The death rate for thyroid cancer remains low compared to other cancers.

Characteristics/Clinical Presentation

Generally, Thyroid cancer does not cause any symptoms, but a person may have a lump or nodule around the thyroid in the neck area. The most common sign of thyroid cancer is a nodule that may be noticed by a physician, or even the patient themselves as they put on a necklace, button a shirt or coat, or looking in the mirror. On rare occasions, thyroid cancer may actually present with symptoms such as pain in the jaw, neck or ear areas. The nodule can compress the airway if it gets large enough which can lead to difficulty breathing or swallowing and hoarseness. The patient may complain of a "tickle in the throat".

Associated Co-morbidities

An associated co-morbidity is a disorder or disease that predisposes a person to develop thyroid cancer.

• Several inherited conditions have been linked to different types of thyroid cancer, including family history. However, most people who develop thyroid cancer do not have an inherited condition or a family history of the disease.

Medullary thyroid cancer

• About 1 out of 3 medullary thyroid carcinomas (MTCs) result from inheriting an abnormal gene. These cases are known as familial medullary thyroid carcinoma (FMTC).
• The combination of FMTC and tumors of other endocrine glands is called multiple endocrine neoplasia type 2 (MEN 2). There are 2 subtypes, MEN 2a and MEN 2b, both of which are caused by mutations in a gene called RET.
•  In MEN 2a, MTC occurs along with pheochromocytomas (tumors that make adrenaline) and with parathyroid gland tumors.
•  In MEN 2b, MTC is associated with pheochromocytomas and with benign growths of nerve tissue on the tongue and elsewhere called neuromas. This subtype is much less common than MEN 2a.
• In the above inherited forms of MTC, the cancers often develop during childhood or early adulthood and can spread early. MTC is most aggressive in the MEN 2b syndrome. If MEN 2a, MEN 2b, or isolated FMTC runs in your family, you may be at very high risk of developing MTC. 
  

Other thyroid cancers

• Familial adenomatous polyposis (FAP): Persons with this disorder are at an increased risk for papillary thyroid cancer
• Cowden disease: Can cause an increased risk of thyroid problems and papillary or follicular thyroid cancers
• Carney complex, type I: Can cause an increased risk of papillary or follicular thyroid cancers.
• Familial nonmedullary thyroid carcinoma: Thyroid cancer occurs more often in some families, and is often seen at an earlier age. The most common form of thyroid cancer that runs in these families is the papillary type. Genes on chromosome 19 and chromosome 1 are suspected of causing these familial cancers.
• Family history: Having a first-degree relative (parent or sibling) with thyroid cancer, even without a known inherited syndrome in the family, increases your risk of thyroid cancer. The genetic basis for these cancers is not totally clear.

Medications

Below is a list of cancer drugs that are approved by the Food and Drug Administration (FDA) for thyroid cancer.  

Adriamycin PFS (Doxorubicin Hydrochloride)
Adriamycin RDF (Doxorubicin Hydrochloride)
Cabozantinib-S-Malate
Caprelsa (Vandetanib)
Cometriq (Cabozantinib-S-Malate)
Doxorubicin Hydrochloride
Nexavar (Sorafenib Tosylate)
Sorafenib Tosylate
Vandetanib

Diagnostic Tests/Lab Tests/Lab Values

Thyroid cancer is commonly diagnosed using a fine needle aspiration biopsy of a thyroid nodule. The biopsy can also be done after the nodule has been removed during surgery. Thyroid lab test are generally not helpful in the diagnosis of thyroid cancer, the lab tests are usually normal regardless if a cancer is present.

Etiology/Causes

The cause of thyroid cancer is unknown, however, people who have their thyroid gland exposed to high doses of radiation or have a family history of thyroid cancer are at a higher risk of developing thyroid cancer. The risk of thyroid cancer also increases as we age. High doses of radiation such as from reoccurring chest x-rays, especially in childhood, can lead to thyroid cancer. 

Treatments and X-rays for Hodgkin's disease and breast cancer have been shown to have a greater risk for thyroid cancer. Generally, exposure form routine x-rays such as a simple chest x-ray and dental x-rays have not been linked to increasing the risk for thyroid cancer.

Radioactive iodine has also been linked to causing thyroid cancer. Examples of radioactive iodine causing thyroid cancer would include Chernobyl, a Russian nuclear power plant accident in 1986, and the tsunami-related nuclear power plant disaster in 2011 in Japan.

Systemic Involvement

The most common places in the body for thyroid cancer to spread to are the lungs, liver, and bones. 

Lungs: Patients with cancer that has spread to the lungs may not have any associated signs and symptoms. Possible symptoms could include the following though:

• coughing up blood
• chest pain
• shortness of breath
• weakness
• weight loss

Liver:  In the early stages there may not be any signs or symptoms. In the later stages, the liver begins to swell and can cause the following symptoms:

• loss of appetite
• weight loss
• jaundice
• nausea
• confusion
• sweats/fever
• pain in right shoulder or right upper abdomen

Bone:

• Bone pain is often the first symptom. Pain is worse at night and is better with movement.
• Broken bones
• Numbness or paralysis
• Loss of appetite, confusion, nausea

Medical Management

There are various types of treatment options available for those diagnosed with thyroid cancer. There are standard treatments and some that are being tested in clinical trials. There are currently five standard treatments:

Surgery-

Most common form of treatment

Lobectomy (Removal of the lobe of the lung with the cancer)

• Near-toal thyroidectomy (Removal of nearly all the thyroid gland)
• Total thyroidectomy (Removal of all the thyroid gland)
• Lymphadenectomy (Removal of cancerous lymph nodes in the neck)

Radiation therapy

(including radioactive iodine therapy or RAI)

• RAI is used for follicular and papillary thyroid cancers. This is taken by mouth and will collect any remaining thyroid cancer cells that may have spread. Since only the thyroid gland takes up iodine, no other tissue is harmed.
• Radiation uses high energy x-rays to kill cancer cells and keep them from growing (depends on stage and type of cancer).

Chemotherapy

• Uses drugs (by mouth or injection) to stop the growth of cancer cells. (Depends on type and stage of cancer).

Thyroid hormone therapy

• Hormone therapy removes hormones or blocks their action to stop cancer cells from growing. For thyroid cancer, drugs are given to prevent the body from making Thyroid-stimulating hormone (TSH) because this hormone increases the chance that the thyroid cancer will grow or recur.

Targeted therapy

• Uses drugs or other substances to kill cancerous cells and avoid harming normal cells. Vandetanib, a type of Tyrosine Kinase Inhibitor (TKI), is used to block signals needed for thyroid tumors to grow.

Patients with thyroid cancer may want to think about participating in a clinical trial. More information can be found at: http://www.cancer.gov/clinicaltrials

Physical Therapy Management

Exercise has recently been shown through research to be safe and possible during cancer treatment. Research suggests there is a decrease in neck range of motion and increase in trigger points in neck muscles after thyroidectomy. Physical Therapy for cancer treatment can include exercises to improve flexibility, strength, and endurance. Massage may also be used to help decrease stress, pain, and scar tissue during and after cancer treatment. It is important to maintain an active lifestyle to help improve quality of life and reduce stress and fatigue. 

Physical Therapy can help build the body's tolerance to cancer treatments like chemotherapy and radiation through the use of exercise to increase heart rate, muscular strength, and range of motion. Lack of activity can lead to muscle weakness, decreased range of motion, and decreased body function.

Ways regular exercise may help you during cancer treatment

• Keep or improve your physical abilities
• Better balance, lower risk of falls and broken bones
• Keep muscles from wasting due to inactivity
• Lower the risk of heart disease
• Lessen the risk of osteoporosis
• Improve blood flow to your legs and lower the risk of blood clots
• Make you less dependent on others for help with normal activities of daily living
• Improve your self-esteem
• Lower the risk of being anxious and depressed
• Lessen nausea
• Improve your ability to keep social contacts
• Fewer symptoms of fatigue
• Help you control your weight
• Improve your quality of life

Differential Diagnosis

Below are several differential diagnosis of thyroid cancer:

• Goiter
• Hashimoto's Thyroiditis
• Benign Thyroid nodules or cysts
• Graves Disease
• Thyroid Lymphoma
• Subacute Thyroiditis
• Hyperthyroidism
• Hypothyroidism
• Multiple Endocrine Neoplasia Type 2