The thyroid gland is located in the front of the neck at the base of the throat. Thyroid tumors are either benign (noncancerous) or malignant (cancerous) growths. Examples of benign tumors are adenomas, which secrete thyroid hormone. Malignant tumors are more rare and are more common in women than in men. According to the American Cancer Society (ACS), about 22,000 cases of thyroid cancer will be diagnosed in the US in 2003.
What are thyroid adenomas?
Thyroid adenomas grow from the cell layer that lines the inner surface of the thyroid gland. The adenoma itself secretes thyroid hormone. If the adenoma secretes enough thyroid hormone, it may cause hyperthyroidism. Thyroid adenomas may be treated if they cause hyperthyroidism. Treatment may include surgery to remove part of the thyroid (the overactive nodule).
What are cancerous thyroid tumors?
Cancer of the thyroid occurs more often in people who have undergone radiation to the head, neck, or chest. However, most thyroid cancer can be cured with appropriate treatment. Thyroid cancer usually appears as small growths (nodules) within the thyroid gland. Some signs that a nodule may be cancerous include:
- presence of a single nodule rather than multiple nodules
- thyroid scan reveals the nodule is not functioning
- nodule is solid instead of filled with fluid (cyst)
- nodule is hard
- nodule grows fast
What are the different types of thyroid cancer?
The National Cancer Institute (NCI) describes the major types of thyroid cancer as follows:
- papillary and follicular thyroid cancers
These two types of thyroid cancer account for 80 percent to 90 percent of all thyroid cancers. Papillary thyroid cancer is the more common of the two types. Both types begin in the follicular cells of the thyroid and tend to grow slowly.
- follicular thyroid cancer
This type of thyroid cancer occurs most often among elderly patients and accounts for about 15 percent of thyroid cancer cases. This type of thyroid cancer is more aggressive and tends to spread through the bloodstream to other parts of the body.
- medullary thyroid cancer
This type of thyroid cancer accounts for 5 percent to 10 percent of all thyroid cancers. Medullary thyroid cancer is the only thyroid cancer that begins in the C cells. This type of thyroid cancer is easier to control if it is found and treated early, before it spreads to other parts of the body. There are two types of medullary thyroid cancer: sporadic medullary thyroid cancer and familial medullary thyroid cancer (FMTC). Because familial medullary thyroid cancer tends to run in families, screening tests for genetic abnormalities in the blood cells may be conducted.
- anaplastic thyroid cancer
This rare type of thyroid cancer accounts for about 1percent to 2 percent of all thyroid cancers. Anaplastic thyroid cancer begins in the follicular cells and tends to grow and spread very quickly.
What are the symptoms of thyroid cancer?
Early thyroid cancer may not cause any symptoms. As the cancer grows, one of the first signs of thyroid cancer is a painless lump or swollen lymph nodes in the neck. The following are the most common symptoms of thyroid cancer. However, each individual may experience symptoms differently. Other symptoms may include:
- hoarseness or loss of voice as the cancer presses on the nerves to the voice box
- difficulty swallowing as the cancer presses on the throat
However, the symptoms of thyroid cancer may resemble other conditions or medical problems. Always consult your physician for a diagnosis.
Diagnosis of thyroid cancer:
In addition to a complete medical history and medical examination, diagnostic procedures for thyroid cancer may include:
- blood tests – to evaluate the level of thyroid-stimulating hormone (TSH), calcium, calcitonin (a hormone produced by normal C cells of the thyroid gland), and other substances in the blood.
- thyroid scan – a type of nuclear scan that examines the thyroid after a person is given (by mouth or intravenously) a small amount of radioactive material that contains iodine or technetium. For a short period, the radioactive material emits radiation. A special camera, called a gamma camera, is used to determine the amount of radiation that has been absorbed by thyroid nodules. Cold nodules are nodules that absorb less radioactive material than the surrounding thyroid tissue. Whereas, hot nodules are nodules that absorb more radioactive material.
- ultrasound (Also called sonography.) – a diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.
- biopsy – a procedure in which tissue samples are removed (with a needle or during surgery) from the body for examination under a microscope; to determine if cancer or other abnormal cells are present.
Treatment for thyroid cancer:
Specific treatment for thyroid tumors will be determined by your physician based on:
- your age, overall health, and medical history
- extent of the disease
- your tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
Treatment may include one or more of the following:
- surgery – to remove all or part of the thyroid. Types of thyroid surgery include:
- total thyroidectomy – removal of the thyroid and sometimes the nearby lymph nodes.
- lobectomy – removal of the lobe with the cancerous nodule. The nearby lymph nodes and part of the remaining thyroid tissue may also be removed.
- radioactive iodine therapy (also called radioiodine therapy) – a therapy in which small amounts of radioactive iodine (I-131) is given (usually in a capsule or liquid) to destroy any thyroid cancer cells, those that have not been removed by surgery or have spread to other parts of the body. Radioactive iodine therapy is usually not used to treat medullary or anaplastic thyroid cancer.
- external radiation (external beam therapy) – a treatment that precisely sends high levels of radiation directly to the cancer cells. The machine is controlled by the radiation therapist. Since radiation is used to kill cancer cells and to shrink tumors, special shields may be used to protect the tissue surrounding the treatment area. Radiation treatments are painless and usually last a few minutes.
- hormone therapy – hormones are given to kill cancer cells, slow the growth of cancer cells, or stop cancer cells from growing. Hormone therapy as a cancer treatment involves taking substances to interfere with the activity of hormones or to stop the production of hormones. Hormone therapy may be used to treat papillary and follicular thyroid cancer. This therapy may also be necessary after surgery or radioactive iodine therapy to replace the natural thyroid hormone.
- chemotherapy – the use of anticancer drugs to treat cancerous cells. In most cases, chemotherapy works by interfering with the cancer cell’s ability to grow or reproduce. Different groups of drugs work in different ways to fight cancer cells. The oncologist will recommend a treatment plan for each individual.
Source: Stanford Medicine Cancer Institute, 2014.