Thyroid Cancer Health Article

Definition

Thyroid cancer is a disease in which the cells of the thyroid gland become abnormal, grow uncontrollably and form a mass of cells called a tumor.

Description

The thyroid is a hormone-producing, butterfly-shaped gland located in the neck at the base of the throat. It has two lobes, the left and the right. The thyroid uses iodine, a mineral found in some foods, to make several of its hormones. Thyroid hormones regulate essential body processes such as heart rate, blood pressure, body temperature, metabolism, and affect the nervous system, muscles and other organs. These hormones also play an important role in regulating childhood growth and development.

Types of thyroid cancer

Thyroid cancer is grouped into four types based on how its cells appears under a microscope. The types are papillary, follicular, medullary and anaplastic thyroid cancers. They grow at different rates and can spread to other parts of the body if left untreated.

PAPILLARY.

The papillary type (60%-80% of all thyroid cancers) is a slow-growing cancer that develops in the hormone-producing cells that contain iodine.

FOLLICULAR.

The follicular type (30%-50% of thyroid cancers) also develops in the hormone-producing cells.

MEDULLARY.

The medullary type (5%-7% of all thyroid cancers) develops in the parafollicular cells (also known as the C cells) that produce calcitonin, a hormone that does not contain iodine.

ANAPLASTIC.

The fourth type of thyroid cancer, anaplastic (2% of all thyroid cancers), is the fastest growing, most aggressive thyroid cancer type.

Demographics

Diseases of the thyroid gland affect millions of Americans. The most common diseases of the thyroid are either hyperthyroidism (Grave's disease) or hypothyroidism, an overactive or an underactive gland, respectively. Sometimes lumps or masses may develop in the thyroid. Although most (95%) of these lumps or nodules are non-cancerous (benign), all thyroid lumps should be taken seriously. The American Cancer Society estimates that in 2001, approximately 19, 500 new cases of thyroid cancer will have been diagnosed in the United States.

Women are three times more likely to develop thyroid cancer than men. Although the disease affects teenagers and young adults, most people who develop thyroid cancer are over 50 years of age. Caucasians are affected more often than African-Americans.

Causes and symptoms

The exact cause of thyroid cancer is not known but some risk factors have been identified. Radiation was used in the 1950s and 1960s to treat acne and to reduce swelling in infections of the tonsils, adenoids and lymph nodes. It has been proven that this exposure is a risk factor for thyroid cancer. In some areas of the world, diets are low in iodine. Papillary and follicular cancers occur more frequently in these areas. Iodine deficiency is not a large problem in the United States because iodine is added to table salt and other foods. Approximately 7% of thyroid cancers are caused by the alteration (mutation) of a gene called the RET onco-gene, which can be inherited.

Symptoms are rare, and the lump is not usually painful. The symptoms of thyroid nodules are:

• A lump or nodule that can be felt in the neck is the most frequent sign of thyroid cancer.
• The lymph nodes may be swollen and the voice may become hoarse because the tumor presses on the nerves leading to the voice box.
• Some patients experience a tight or full feeling in the neck and have difficulty breathing or swallowing.