Cancer of the thyroid is more common in women than in men. Most patients are between 25 and 65 years old. People who have been exposed to large amounts of radiation, or who have had radiation treatment for medical problems in the head and neck have a higher chance of getting thyroid cancer. The cancer may not occur until 20 years or longer after radiation treatment.

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.

There are four main types of cancer of the thyroid (based on how the cancer cells look under a microscope): papillary, follicular, medullary, and anaplastic. The chance of recovery (prognosis) depends on the type of thyroid cancer, whether it is just in the thyroid or has spread to other parts of the body (stage), and the patient's age and overall health. Some types of thyroid cancer grow much faster than others.

The genes in our cells carry the hereditary information from our parents. An abnormal gene has been found in patients with some forms of thyroid cancer. If medullary thyroid cancer is found, the patient may have been born with a certain abnormal gene which may have led to the cancer. Family members may have also inherited this abnormal gene. Tests have been developed to determine who has the genetic defect long before any cancer appears. It is important that the patient and his or her family members (children, grandchildren, parents, brothers, sisters, nieces and nephews) see a doctor about tests that will show if the abnormal gene is present. These tests are confidential and can help the doctor help patients. Family members, including young children, who don't have cancer, but do have this abnormal gene, may reduce the chance of developing medullary thyroid cancer by having surgery to safely remove the thyroid gland (thyroidectomy).