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Types of Thyroid Cancer

Overview of the Four Types of Thyroid Cancer

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Updated May 07, 2012

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Thyroid cancer is a type of cancer that affects the thyroid, a butterfly-shaped gland located in the front of the neck. The thyroid produces essential hormones that regulate our metabolic rate. The thyroid is vulnerable to disease, such as hyperthyroidism, hypothyroidism, and even cancer.

There are four types of thyroid cancer: papillary, follicular, medullary, and anaplastic. The types of thyroid cancer are classified by which cells they originate from and their appearance. Each type is unique with varying treatment methods, prognoses, and survival rates.

Diagnosis of thyroid cancer is made by a biopsy, using a fine needle aspiration method in most cases. Once a sample of the thyroid tissue is collected through a biopsy, it is then examined under a microscope by a pathologist (a physician who specializes in diagnosing diseases by examining blood, tissue, and fluid samples).

Papillary Thyroid Cancer

This is the most common type of thyroid cancer, accounting for approximately 80-90% of all cases. Papillary thyroid cancer is very treatable, and in many cases, curable. While papillary thyroid cancer often spreads to the cervical lymph nodes, it does not commonly spread to distant organs, like in other types of cancer. If it does metastasize, the bones and the lungs are likely sites of metastasis.

Papillary thyroid cancer is strongly associated with radiation exposure. It is most often seen in adults aged 30-50.

Follicular Thyroid Cancer

Follicular thyroid cancer is the second most commonly diagnosed type of thyroid cancer, accounting for approximately 15% of diagnoses. It is usually detected by the presence of a small, painless lump in the neck. The disease occurs more often in women than in men. Most people diagnosed with this type of thyroid cancer are under the age of 40.

Metastasis occurs more often in follicular thyroid cancer than in papillary cancer, largely due to vascular invasion, allowing the disease to spread through the bloodstream. The bones and lungs are possible sites for metastasis, as in papillary thyroid cancer. Age greatly affects the prognosis of a person with follicular thyroid cancer; younger patients tend to fare better than older patients.

Unlike papillary carcinoma, follicular cancer is not as strongly related to radiation exposure.

Medullary Thyroid Cancer

It is estimated that medullary thyroid cancer accounts for 3% of thyroid cancer diagnoses, making it the third most common type. It is not related to radiation exposure and originates in the cells of the thyroid gland that produce the hormone calcitonin, called C cells. Women are diagnosed more often than men, and most are diagnosed at 40-60 years of age.

Anaplastic Thyroid Cancer

This type of thyroid cancer is the most rare and accounts for about 1-5% of thyroid cancer diagnoses. It is aggressive and spreads rapidly. Anaplastic thyroid cancer usually affects people over the age of 60. Treatment options are limited as the disease does not respond well to treatment, making the prognosis poor for patients with anaplastic thyroid cancer.

Staging Thyroid Cancer

Once the pathologist identifies the type of thyroid cancer, the next step in the diagnostic process is to stage the disease. During the staging process, it is determined whether the cancer has spread, and if so, how far. Thyroid cancer treatment plans rely heavily on the type of thyroid cancer and stage.
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