thyroid cancer

The thyroid gland 

The thyroid is a small gland in the front of the neck just below the voice box (larynx).

It is made up of two parts, or lobes. It's one of a network of glands throughout the body that make up the endocrine system. This system is responsible for producing the body’s hormones that help to control and influence various functions.  

The thyroid is sometimes known as the ‘activity’ gland because it produces the two main hormones, thyroxine (T4) and triiodothyronine (T3), which are needed to keep the body functioning at its normal rate. In order to produce the thyroid hormones, the thyroid gland needs a regular supply of iodine (which is found in fish, seafood and dairy products). If the levels of T3 and T4 in the blood fall, the hypothalamus (a part of the brain) sends out thyroid-releasing hormone (TRH) into the blood. As the level of TRH in the blood rises, the pituitary gland releases thyroid-stimulating hormone (TSH) which stimulates the thyroid to produce more thyroid hormones.

If the thyroid gland doesn’t produce enough hormones, you will feel tired and lethargic and put on weight easily. This is called hypothyroidism, or myxoedema. If the thyroid gland produces too many hormones you will lose weight, have an increased appetite, feel shaky and anxious, or have palpitations. This is known as hyperthyroidism, or thyrotoxicosis.

What is thyroid cancer?

Thyroid cancer is a disease that you get when abnormal cells begin to grow in your thyroid gland .The thyroid gland is shaped like a butterfly and is located in the front of your neck. It makes hormones that regulate the way your body uses energy and that help your body work normally.
Thyroid cancer is an uncommon type of cancer. Most people who have it do very well, because the cancer is usually found early and the treatments work well. After it is treated, thyroid cancer may come back, sometimes many years after treatment.

Types of thyroid cancer

The type of thyroid cancer determines treatment and prognosis. Types of thyroid cancer include:

• Papillary thyroid cancer. The papillary type of thyroid cancer is the most common, making up about 80 percent of all thyroid cancer diagnoses.
• Follicular thyroid cancer. Follicular thyroid cancer also includes Hurthle cell cancer.
• Medullary thyroid cancer. Medullary thyroid cancer may be associated with inherited genetic syndromes that include tumors in other glands. However, most medullary thyroid cancers are sporadic, meaning they aren't associated with inherited genetic syndromes.
• Anaplastic thyroid cancer. The anaplastic type of thyroid cancer is very rare, aggressive and very difficult to treat.
• Thyroid lymphoma. Thyroid lymphoma begins in the immune system cells in the thyroid. Thyroid lymphoma is very rare.

Thyroid Cancer Risk Factors

Although the causes of thyroid cancer are not well understood, there are 2 main factors which are known to put an individual at higher risk of developing the disease:

1. a family history of thyroid cancer and
2. exposure to radiation.

Family History:

As with many types of cancer, a family history of thyroid cancer is a known risk factor. A family history of thyroid cancer carries the biggest risk for patients with first degree relatives (mother, father, sister, brother), second degree relatives (grandmother, grandfather, grandson, granddaughter), and/or multiple family members with thyroid cancer. About 5% of patients who develop papillary thyroid cancer and 20-25% of patients who develop medullary thyroid cancer have a relative who also had thyroid cancer.

Radiation Exposure:

In the 1960's it was discovered that exposure of the head and neck areas to radiation during treatment of benign diseases increases the risk of developing thyroid cancer. In addition to radiation treatment, exposure to radiation as a result of nuclear weapons or nuclear plant accidents, such as that experienced by the survivors of Hiroshima, Nagasaki and Chernobyl, also increases the risk for developing thyroid cancer.

Treatment of thyroid cancer

Surgery

Almost all cases of thyroid cancer are treated with surgery. Many are also treated with additional methods.
The surgery will most likely be one of the following:

• Total thyroidectomy. The entire thyroid is removed.
• Near-total thyroidectomy. Most of the thyroid is removed.
• Lobectomy. Only the side of the thyroid where the cancer is located is removed. This type of surgery may be used in papillary cancers smaller than 1 centimeter (about ½ inch) that have not spread.

Radiation

Radiation therapy uses high-energy X-rays or other types of radiation to kill cancer cells or shrink tumors. Thyroid cancer may be treated with:

• Radioactive iodine. The patient drinks a liquid that contains radioactive iodine, which collects in thyroid tissue and kills cancer cells.
• External beam radiation. Radiation comes from outside the body.

The type of radiation used depends on the type and stage of your cancer. External beam radiation is most effective for thyroid cancers that do not absorb iodine, including anaplastic thyroid cancer. It is also used if any type of thyroid cancer remains after surgery or if cancer has spread to the bones.

Hormone therapy

Thyroid hormone therapy uses hormones to halt the growth of cancer cells. In papillary or follicular thyroid cancer, hormone treatment may be used to lower the level of thyroid stimulating hormone, which increases the chance of recurrence. In other thyroid cancers, thyroid hormone may be used to maintain normal levels of thyroid hormone in the body.
Hormone therapy is given as a pill. Taking thyroid hormone at the proper dose usually does not cause side effects. If the dose is too high, side effects may include heart palpitations, nervousness, insomnia, and osteoporosis (thinning of the bones).

Chemotherapy

Chemotherapy often is used in combination with external beam radiation therapy to treat anaplastic thyroid cancer. It is usually not particularly effective in other types of thyroid cancer.
Chemotherapy uses drugs to stop the growth of cancer cells by killing the cells or stopping them from dividing. The drugs can be given by mouth or injected into a vein or muscle. Usually, chemotherapy is given to a patient through a vein during an outpatient visit.