Thyroid Cancer

Thyroid cancer is a disease in which cancer (malignant) cells are found in the tissues of the thyroid gland. The thyroid gland is at the base of the throat. It has two lobes, one on the right side and one on the left. The thyroid gland makes important hormones that help the body function normally.

There are four main types of thyroid cancer (based on how the cancer cells look under a microscope):

1. Papillary - Cancer that forms in cells in the thyroid and grows in small finger-like shapes. It grows slowly, is more common in women than in men, and often occurs before age 40. It is the most common type of thyroid cancer.
2. Follicular - Cancer that develops from cells in the follicular areas of the thyroid. One of the slow-growing, highly treatable types of thyroid cancer.
3. Medullary - Cancer that develops in C cells of the thyroid. The C cells make a hormone (calcitonin) that helps maintain a healthy level of calcium in the blood.
4. Anaplastic - A rare, aggressive type of thyroid cancer in which the malignant (cancer) cells look very different from normal thyroid cells.

Symptoms and Diagnosis

A doctor should be seen if there is a lump or swelling in the front of the neck or in other parts of the neck.

If there are symptoms, a doctor will feel the patient's thyroid and check for lumps in the neck. The doctor may order blood tests and special scans to see whether a lump in the thyroid is making too many hormones. The doctor may want to take a small amount of tissue from the thyroid. This is called a biopsy. To do this, a small needle is inserted into the thyroid at the base of the throat and some tissue is drawn out. The tissue is then looked at under a microscope to see whether it contains cancer.

Causes

All cancers are caused by dysfunctions of proteins involved in cell division, apoptosis, or DNA repair (see general characteristics). Dysfunctional proteins may arise from gene mutations or protein interactions with environments. The gene BRAF is associated with the papillary thyroid cancer and the gene RET is linked to the medullary thyroid cancer.

The following factors may increase the risk of developing thyroid cancer:

• Thyroid cancer occurs more often in people between the ages of 25 and 65 years.
• People who have been exposed to radiation or received radiation treatments to the head and neck during infancy or childhood have a greater chance of developing thyroid cancer. The cancer may occur as early as 5 years after exposure or may occur 20 or more years later.
• People who have had goiter (enlarged thyroid) or a family history of thyroid disease have an increased risk of developing thyroid cancer.
• Thyroid cancer is more common in women than in men.
• Asian people have an increased risk of developing thyroid cancer.

Reference:

National Cancer Institute, USA.