What is Thyroid Cancer?

Thyroid cancer is a malignant growth or tumor in the thyroid gland. In a healthy thyroid, old cells die and are constantly replaced by new cells. However, in some cases, certain cells become abnormal and continue to grow and reproduce uncontrollably. These cells eventually form a tumor.

The National Cancer Institute (NCI) estimates that there are approximately 388,386^[1] people in the United States who have a history of thyroid cancer, and over 37,340 who will be diagnosed with thyroid cancer in 2008.^[2] Although thyroid cancer represents only 2% of all cancers, it is the most common cancer of the endocrine system (the endocrine system consists of glands throughout the body that produce hormones).

Thyroid cancer occurs in both men and women and can occur at any age. However, thyroid cancer occurs almost three times more often in women than in men.^[2] Among both men and women, the number of new cases of thyroid cancer is increasing at a faster rate than any other type of cancer.

The good news is that there is a very high treatment success rate for most types of thyroid cancer when found and treated early. Despite high treatment success, it is important to know that up to 1/3 of thyroid cancers can recur, sometimes even decades after the initial treatment. For this reason, thyroid cancer requires long-term diagnostic follow-up to make sure that the cancer has not come back; and if it has, so that treatment can be started right away.

Different Types of Thyroid Cancer

Not all thyroid cancers are the same. There are four main types of the disease:

• Papillary
• Follicular
• Medullary
• Anaplastic

Papillary and follicular cancers, often referred to as “well-differentiated” thyroid cancers (WDTC), are the most common. Together, they account for about 90% of thyroid cancers. Generally, the prognosis, or long-term outlook, for patients diagnosed with WDTC is very good. With regular checkups and follow-up monitoring, the 20-year survival rate is nearly 93%.^[1]

Medullary and anaplastic thyroid cancers are much less common, and are usually more difficult to treat, although great strides have been made in the treatment of all thyroid cancers.

The prognosis for any given thyroid cancer patient depends on several factors, including the type of thyroid cancer, whether the disease has spread to other parts of the body, and the patient’s age at diagnosis. Early and aggressive treatment as well as commitment to lifelong follow up is essential to achieve the best outcome.

REFERENCES:

1. National Cancer Institute. Seer Cancer Statistics Review. Available at: http://seer.cancer.gov. Accessed April 30, 2008.

2. American Cancer Society. Detailed Guide: Thyroid Cancer. Available at: http://www.cancer.org. Accessed April 30, 2008.